feat(water-log): cycle 4 — Tuxedo mobile worker Time tab + unified PIN

The mobile `/water` worker experience (Tuxedo-only, matching the
existing water flow) now exposes a "Time" tab alongside "Headgates"
so irrigators can clock in/out from the same phone they use for
water entries — no second PIN.

- MobileWaterApp: new `activeTab` state, sticky TabBar rendered only
  after PIN, screen='time' case embeds <TimeTrackingFieldClient>
  with hardcoded Tuxedo brand constants.
- handlePinSubmit best-effort calls `verifyTimeTrackingPin` after
  the water PIN succeeds, so the Time tab never re-prompts a worker
  who is also set up in `time_tracking_workers`.
- handleLogout clears BOTH `wl_session` and `time_tracking_session`
  cookies in independent try/catch blocks.
- Tab switching to Time drops in-flight water flow state; switching
  back to Headgates restores the list without reload.
- i18n: added `tab.{headgates,time,logout}` strings (en + es); lifted
  Tuxedo brand display constants into @/lib/water-log/brand so the
  standalone /tuxedo/time-clock page and the embedded Time tab share
  one source of truth.

src/lib/water-log/brand.ts

@@ -11,4 +11,13 @@
  * `TUXEDO_BRAND_ID` with `effectiveBrandId` from `getAdminUser()` —
  * which is the standard pattern used throughout the rest of the app.
  */
-export const TUXEDO_BRAND_ID = "64294306-5f42-463d-a5e8-2ad6c81a96de";
+export const TUXEDO_BRAND_ID = "64294306-5f42-463d-a5e8-2ad6c81a96de";
+
+/** Display surfaces (Cycle 4) — single source of truth for the
+ *  Tuxedo worker experience so the standalone `/tuxedo/time-clock`
+ *  page and the embedded Time tab inside `/water` stay in sync.
+ *  Bump these together when the brand refreshes its accent/logo. */
+export const TUXEDO_BRAND_NAME = "Tuxedo Corn";
+export const TUXEDO_BRAND_ACCENT = "green";
+/** `null` until the Tuxedo brand gets a logo asset uploaded. */
+export const TUXEDO_BRAND_LOGO_URL: string | null = null;

src/lib/water-log/i18n.ts

@@ -138,6 +138,13 @@ export type Labels = {
     minutesAgo: (n: number) => string;
     hoursAgo: (n: number) => string;
   };
+  /** Tuxedo worker post-PIN shell (Cycle 4) — names for the two
+   * top tabs and the inline logout affordance. */
+  tab: {
+    headgates: string;
+    time: string;
+    logout: string;
+  };
 };
 
 export const LABELS: Record<Lang, Labels> = {
@@ -231,6 +238,11 @@ export const LABELS: Record<Lang, Labels> = {
       minutesAgo: (n) => `${n}m ago`,
       hoursAgo: (n) => `${n}h ago`,
     },
+    tab: {
+      headgates: "Headgates",
+      time: "Time",
+      logout: "Log out",
+    },
   },
   es: {
     common: {
@@ -323,6 +335,11 @@ export const LABELS: Record<Lang, Labels> = {
       minutesAgo: (n) => `hace ${n}m`,
       hoursAgo: (n) => `hace ${n}h`,
     },
+    tab: {
+      headgates: "Compuertas",
+      time: "Tiempo",
+      logout: "Salir",
+    },
   },
 };