feat(smartsheet): cycle 7 — workbook hub

Replaces two independent Smartsheet configs (water log + time tracking)
with one brand-level workbook connection that owns the encrypted API
token. Per-feature configs keep their sheet_id + column_mapping +
frequency + sync_enabled.

Schema (migration 0096):
- NEW smartsheet_workspace: one row per brand. Holds encrypted_api_token
  + token_iv + token_auth_tag (AES-256-GCM, same key), default_sheet_id,
  connection_enabled (master switch), last_test_*, audit columns. RLS
  brand-scoped.
- Backfill: water_smartsheet_config rows copy into workspace first;
  time_tracking_smartsheet_config fills in only brands with no workspace
  row yet. Idempotent (NOT EXISTS + ON CONFLICT DO NOTHING).
- DROP encrypted_api_token + token_iv + token_auth_tag from both feature
  configs (destructive — bytes are copied to workspace first).
- Drop unused bytea customType from both schemas (no longer needed).

Actions:
- NEW src/actions/smartsheet/workspace.ts: getSmartsheetWorkspace,
  saveSmartsheetWorkspace, testSmartsheetWorkspaceConnection,
  disableSmartsheetWorkspace. Permission: can_manage_settings +
  platform_admin.
- NEW src/services/workspace-token.ts (server-only): resolveWorkspaceToken
  helper. Lives outside the 'use server' file so the plaintext token
  is not exposed as an RPC surface — only callable from server-side
  sync engines.
- MODIFIED water-log + time-tracking smartsheet actions: refactored to
  read token via resolveWorkspaceToken; save* no longer accepts a
  token; test* falls through to the workspace token if no token given.
- MODIFIED both sync services: load token from resolveWorkspaceToken
  instead of decrypting the per-feature config. 'connection_disabled'
  now skips cleanly (no retry, no failed log row) — pausing the
  workspace at the hub level no longer floods Recent Activity with
  'disabled' failures.

UI:
- NEW src/components/admin/water-log/SmartsheetHub.tsx: top-level hub
  card. Owns the token + Test Connection + connection enabled toggle +
  default sheet ID + last-verified badge. Permission gated.
- MODIFIED SmartsheetIntegrationCard.tsx (water): rewritten without
  token UI. Reads masked token from workspace. Sheet ID + column
  mapping + frequency + enabled + backfill + recent activity.
- MODIFIED TimeTrackingSmartsheetCard.tsx: same treatment.
- MODIFIED /admin/water-log/settings/page: collapses §05 + §06 into a
  single Smartsheet section with the hub on top + both feature cards
  as siblings underneath.

Tuxedo-only throughout (TUXEDO_BRAND_ID hardcoded in the settings
page; matches existing single-tenant /water convention).

Security fixes from pr-reviewer:
- resolveWorkspaceToken extracted from 'use server' file to a
  server-only service module — was reachable as an RPC, would have
  returned the plaintext token to any authenticated admin.
- getSmartsheetWorkspace now actually checks the auth result instead
  of calling requireManageSettings() and discarding the return value.

Diff: -1742 / +597 lines (net -1100 from the simpler per-feature card).

db/schema/smartsheet-workspace.ts

@@ -0,0 +1,66 @@
+/**
+ * Smartsheet workspace — per-brand workbook connection.
+ *
+ * Cycle 7 schema for migration 0096. Replaces two independent Smartsheet
+ * configs (water + time tracking) with one brand-level workbook hub.
+ *
+ * The encrypted API token lives here. Per-feature configs
+ * (`water_smartsheet_config`, `time_tracking_smartsheet_config`) keep
+ * their sheet_id, column_mapping, sync_frequency, sync_enabled, and
+ * last_sync_* state but read the token from this table via brand_id.
+ *
+ * RLS: brand-scoped, same pattern as existing smartsheet tables.
+ */
+import {
+  pgTable,
+  uuid,
+  text,
+  boolean,
+  timestamp,
+  customType,
+} from "drizzle-orm/pg-core";
+import { brands } from "./brands";
+
+const bytea = customType<{ data: Buffer; default: false }>({
+  dataType() {
+    return "bytea";
+  },
+});
+
+export const smartsheetWorkspace = pgTable("smartsheet_workspace", {
+  brandId: uuid("brand_id")
+    .primaryKey()
+    .references(() => brands.id, { onDelete: "cascade" }),
+
+  // AES-256-GCM encrypted API token. Same key as the old feature
+  // configs (SMARTSHEET_TOKEN_ENC_KEY); bytes are portable.
+  encryptedApiToken: bytea("encrypted_api_token").notNull(),
+  tokenIv: bytea("token_iv").notNull(),
+  tokenAuthTag: bytea("token_auth_tag").notNull(),
+
+  // Optional "home" sheet — the tab the brand sees first in the
+  // workbook. NULL is fine; the UI falls back to the first per-
+  // feature sheet mapping.
+  defaultSheetId: text("default_sheet_id"),
+
+  // Master kill-switch. Per-feature sync_enabled still gates each
+  // feature independently — toggling this off pauses all syncs.
+  connectionEnabled: boolean("connection_enabled").notNull().default(true),
+
+  // Test-connection bookkeeping (powers the "Last verified 2m ago"
+  // badge on the hub card).
+  lastTestAt: timestamp("last_test_at", { withTimezone: true }),
+  lastTestError: text("last_test_error"),
+
+  createdBy: text("created_by"),
+  updatedBy: text("updated_by"),
+  createdAt: timestamp("created_at", { withTimezone: true })
+    .notNull()
+    .defaultNow(),
+  updatedAt: timestamp("updated_at", { withTimezone: true })
+    .notNull()
+    .defaultNow(),
+});
+
+export type SmartsheetWorkspace = typeof smartsheetWorkspace.$inferSelect;
+export type SmartsheetWorkspaceInsert = typeof smartsheetWorkspace.$inferInsert;