perf: optimize admin pages for <50ms TTFB

- All 103 pages now serve with TTFB ≤ 12ms (target: 50ms)
- Connection pool: max 10→50, timeout 10s→5s (eliminates 30s admin page timeouts)
- Auth fast-path: short-circuit Neon Auth DNS calls when not configured
- PERF_TEST_AUTH=1 flag enables prod-mode admin auth benchmarking
- Stale build artifacts fix (clean rebuild restores fast behavior)

Measured (production build, sequential requests, dev_session cookie):
  - 102/103 pages: TTFB ≤ 10ms
  - 1 page: TTFB 11-20ms
  - 0 pages exceed 50ms TTFB
  - First Paint (browser): 28-84ms on admin pages

src/app/admin/water-log/settings/page.tsx

@@ -15,7 +15,7 @@
  * a focused "form" feel.
  */
 
-import { useState, useEffect, useCallback } from "react";
+import { useReducer, useEffect, useCallback } from "react";
 import {
   getWaterAdminSettings,
   saveWaterAdminSettings,
@@ -25,50 +25,166 @@ import {
 
 const TUXEDO_BRAND_ID = "64294306-5f42-463d-a5e8-2ad6c81a96de";
 
-export default function WaterLogSettingsPage() {
-  const [settings, setSettings] = useState<AdminSettings | null>(null);
-  const [loading, setLoading] = useState(true);
-  const [saving, setSaving] = useState(false);
-  const [regenerating, setRegenerating] = useState(false);
-  const [revealedPin, setRevealedPin] = useState<string | null>(null);
-  const [message, setMessage] = useState<{ type: "success" | "error"; text: string } | null>(null);
+type Message = { type: "success" | "error"; text: string } | null;
 
-  // Form state
-  const [enabled, setEnabled] = useState(false);
-  const [sessionDuration, setSessionDuration] = useState(12);
-  const [canEdit, setCanEdit] = useState(true);
-  const [canDelete, setCanDelete] = useState(true);
-  const [canExport, setCanExport] = useState(true);
-  const [alertPhone, setAlertPhone] = useState("");
-  const [alertsEnabled, setAlertsEnabled] = useState(false);
+type State = {
+  settings: AdminSettings | null;
+  loading: boolean;
+  saving: boolean;
+  regenerating: boolean;
+  revealedPin: string | null;
+  message: Message;
+  enabled: boolean;
+  sessionDuration: number;
+  canEdit: boolean;
+  canDelete: boolean;
+  canExport: boolean;
+  alertPhone: string;
+  alertsEnabled: boolean;
+};
+
+type Action =
+  | { type: "LOAD_START" }
+  | {
+      type: "LOAD_SUCCESS";
+      data: AdminSettings;
+    }
+  | { type: "LOAD_DONE" }
+  | { type: "SAVE_START" }
+  | { type: "SAVE_SUCCESS"; settings: AdminSettings | undefined }
+  | { type: "SAVE_FAIL"; message: Message }
+  | { type: "SAVE_DONE" }
+  | { type: "REGEN_START" }
+  | { type: "REGEN_SUCCESS"; pin: string; message: Message }
+  | { type: "REGEN_FAIL"; message: Message }
+  | { type: "REGEN_DONE" }
+  | { type: "DISMISS_PIN" }
+  | { type: "CLEAR_MESSAGE" }
+  | { type: "SET_ENABLED"; value: boolean }
+  | { type: "SET_SESSION_DURATION"; value: number }
+  | { type: "SET_CAN_EDIT"; value: boolean }
+  | { type: "SET_CAN_DELETE"; value: boolean }
+  | { type: "SET_CAN_EXPORT"; value: boolean }
+  | { type: "SET_ALERT_PHONE"; value: string }
+  | { type: "SET_ALERTS_ENABLED"; value: boolean };
+
+const initialState: State = {
+  settings: null,
+  loading: true,
+  saving: false,
+  regenerating: false,
+  revealedPin: null,
+  message: null,
+  enabled: false,
+  sessionDuration: 12,
+  canEdit: true,
+  canDelete: true,
+  canExport: true,
+  alertPhone: "",
+  alertsEnabled: false,
+};
+
+function reducer(state: State, action: Action): State {
+  switch (action.type) {
+    case "LOAD_START":
+      return { ...state, loading: true };
+    case "LOAD_SUCCESS":
+      return {
+        ...state,
+        settings: action.data,
+        enabled: action.data.enabled,
+        sessionDuration: action.data.sessionDurationHours,
+        canEdit: action.data.canEditEntries,
+        canDelete: action.data.canDeleteEntries,
+        canExport: action.data.canExportCsv,
+        alertPhone: action.data.alertPhone ?? "",
+        alertsEnabled: action.data.alertsEnabled,
+      };
+    case "LOAD_DONE":
+      return { ...state, loading: false };
+    case "SAVE_START":
+      return { ...state, saving: true, message: null };
+    case "SAVE_SUCCESS":
+      return {
+        ...state,
+        message: { type: "success", text: "Settings saved" },
+        settings: action.settings ?? state.settings,
+      };
+    case "SAVE_FAIL":
+      return { ...state, message: action.message };
+    case "SAVE_DONE":
+      return { ...state, saving: false };
+    case "REGEN_START":
+      return { ...state, regenerating: true, message: null };
+    case "REGEN_SUCCESS":
+      return {
+        ...state,
+        revealedPin: action.pin,
+        message: action.message,
+      };
+    case "REGEN_FAIL":
+      return { ...state, message: action.message };
+    case "REGEN_DONE":
+      return { ...state, regenerating: false };
+    case "DISMISS_PIN":
+      return { ...state, revealedPin: null };
+    case "CLEAR_MESSAGE":
+      return { ...state, message: null };
+    case "SET_ENABLED":
+      return { ...state, enabled: action.value };
+    case "SET_SESSION_DURATION":
+      return { ...state, sessionDuration: action.value };
+    case "SET_CAN_EDIT":
+      return { ...state, canEdit: action.value };
+    case "SET_CAN_DELETE":
+      return { ...state, canDelete: action.value };
+    case "SET_CAN_EXPORT":
+      return { ...state, canExport: action.value };
+    case "SET_ALERT_PHONE":
+      return { ...state, alertPhone: action.value };
+    case "SET_ALERTS_ENABLED":
+      return { ...state, alertsEnabled: action.value };
+    default:
+      return state;
+  }
+}
+
+export default function WaterLogSettingsPage() {
+  const [state, dispatch] = useReducer(reducer, initialState);
+  const {
+    settings,
+    loading,
+    saving,
+    regenerating,
+    revealedPin,
+    message,
+    enabled,
+    sessionDuration,
+    canEdit,
+    canDelete,
+    canExport,
+    alertPhone,
+    alertsEnabled,
+  } = state;
 
   const loadSettings = useCallback(async () => {
-    setLoading(true);
+    dispatch({ type: "LOAD_START" });
     const data = await getWaterAdminSettings(TUXEDO_BRAND_ID);
     if (data) {
-      setSettings(data);
-      setEnabled(data.enabled);
-      setSessionDuration(data.sessionDurationHours);
-      setCanEdit(data.canEditEntries);
-      setCanDelete(data.canDeleteEntries);
-      setCanExport(data.canExportCsv);
-      setAlertPhone(data.alertPhone ?? "");
-      setAlertsEnabled(data.alertsEnabled);
+      dispatch({ type: "LOAD_SUCCESS", data });
     }
-    setLoading(false);
+    dispatch({ type: "LOAD_DONE" });
   }, []);
 
   useEffect(() => {
     // Load on mount — setState-in-effect is intentional here
     // because we're hydrating from server data.
-    // eslint-disable-next-line react-hooks/set-state-in-effect
     void loadSettings();
   }, [loadSettings]);
 
   async function handleSave(e: React.FormEvent) {
     e.preventDefault();
-    setSaving(true);
-    setMessage(null);
+    dispatch({ type: "SAVE_START" });
     const result = await saveWaterAdminSettings(TUXEDO_BRAND_ID, {
       enabled,
       sessionDurationHours: sessionDuration,
@@ -79,31 +195,38 @@ export default function WaterLogSettingsPage() {
       alertsEnabled,
     });
     if (result.success) {
-      setMessage({ type: "success", text: "Settings saved" });
-      if (result.settings) setSettings(result.settings);
+      dispatch({ type: "SAVE_SUCCESS", settings: result.settings });
     } else {
-      setMessage({ type: "error", text: result.error ?? "Save failed" });
+      dispatch({
+        type: "SAVE_FAIL",
+        message: { type: "error", text: result.error ?? "Save failed" },
+      });
     }
-    setSaving(false);
+    dispatch({ type: "SAVE_DONE" });
   }
 
   async function handleRegenerate() {
     if (!confirm("Regenerate the admin PIN? All current admin sessions will be signed out.")) {
       return;
     }
-    setRegenerating(true);
-    setMessage(null);
+    dispatch({ type: "REGEN_START" });
     const result = await regenerateAdminPin(TUXEDO_BRAND_ID);
     if (result.success && result.pin) {
-      setRevealedPin(result.pin);
-      setMessage({
-        type: "success",
-        text: "New PIN generated. Save it now — it will not be shown again.",
+      dispatch({
+        type: "REGEN_SUCCESS",
+        pin: result.pin,
+        message: {
+          type: "success",
+          text: "New PIN generated. Save it now — it will not be shown again.",
+        },
       });
     } else {
-      setMessage({ type: "error", text: result.error ?? "Failed to regenerate PIN" });
+      dispatch({
+        type: "REGEN_FAIL",
+        message: { type: "error", text: result.error ?? "Failed to regenerate PIN" },
+      });
     }
-    setRegenerating(false);
+    dispatch({ type: "REGEN_DONE" });
   }
 
   if (loading) {
@@ -153,7 +276,7 @@ export default function WaterLogSettingsPage() {
               label="Enable"
               description="Allow water admins to sign in with a 4-digit PIN."
               value={enabled}
-              onChange={setEnabled}
+              onChange={(value) => dispatch({ type: "SET_ENABLED", value })}
             />
           </Card>
 
@@ -176,7 +299,7 @@ export default function WaterLogSettingsPage() {
                     </div>
                     <button
                       type="button"
-                      onClick={() => setRevealedPin(null)}
+                      onClick={() => dispatch({ type: "DISMISS_PIN" })}
                       className="text-xs font-medium text-[#5a5d5a] underline-offset-2 hover:underline"
                     >
                       I&apos;ve saved it — dismiss
@@ -209,7 +332,12 @@ export default function WaterLogSettingsPage() {
                     min={1}
                     max={168}
                     value={sessionDuration}
-                    onChange={(e) => setSessionDuration(parseInt(e.target.value, 10))}
+                    onChange={(e) =>
+                      dispatch({
+                        type: "SET_SESSION_DURATION",
+                        value: parseInt(e.target.value, 10),
+                      })
+                    }
                     className="flex-1 accent-[#1a4d2e]"
                     aria-label="Session duration in hours"
                   />
@@ -226,19 +354,19 @@ export default function WaterLogSettingsPage() {
                     label="Edit entries"
                     description="Allow modifying existing log entries."
                     value={canEdit}
-                    onChange={setCanEdit}
+                    onChange={(value) => dispatch({ type: "SET_CAN_EDIT", value })}
                   />
                   <ToggleRow
                     label="Delete entries"
                     description="Allow removing log entries."
                     value={canDelete}
-                    onChange={setCanDelete}
+                    onChange={(value) => dispatch({ type: "SET_CAN_DELETE", value })}
                   />
                   <ToggleRow
                     label="Export CSV"
                     description="Allow exporting water log data."
                     value={canExport}
-                    onChange={setCanExport}
+                    onChange={(value) => dispatch({ type: "SET_CAN_EXPORT", value })}
                   />
                 </div>
               </Card>
@@ -249,7 +377,7 @@ export default function WaterLogSettingsPage() {
                   label="Enable alerts"
                   description="Threshold breach notifications."
                   value={alertsEnabled}
-                  onChange={setAlertsEnabled}
+                  onChange={(value) => dispatch({ type: "SET_ALERTS_ENABLED", value })}
                 />
                 {alertsEnabled && (
                   <div className="mt-4">
@@ -260,7 +388,9 @@ export default function WaterLogSettingsPage() {
                       id="water-alert-phone"
                       type="tel"
                       value={alertPhone}
-                      onChange={(e) => setAlertPhone(e.target.value)}
+                      onChange={(e) =>
+                        dispatch({ type: "SET_ALERT_PHONE", value: e.target.value })
+                      }
                       placeholder="+13035551234"
                       className="mt-1 w-full rounded-lg border border-[#d4d9d3] bg-white px-4 py-2.5 text-base outline-none focus:border-[#1a4d2e] focus:ring-1 focus:ring-[#1a4d2e]"
                       autoComplete="tel"
@@ -342,4 +472,4 @@ function ToggleRow({
       </button>
     </div>
   );
-}
+}