Task #613: replace per-app hide toggles with single Dock visibility switch

The per-app hidden feature shipped in #609 was rejected — user wanted one
toggle that hides/shows the entire bottom AppDock bar, leaving Home apps
untouched.

Removed:
- lib/db/src/schema/user-hidden-apps.ts (and index.ts export); table
  dropped via `pnpm --filter @workspace/db run push`
- GET /me/apps and PUT /me/apps/:appId/hidden routes
- getHiddenAppIdsForUser + getVisibleNonHiddenAppsForUser helpers
- MyApp + UpdateMyAppHiddenBody OpenAPI schemas
- MyAppsBody settings UI + related i18n keys
- Regenerated api-client-react + api-zod from the trimmed spec
- Reverted GET /apps back to getVisibleAppsForUser

Added:
- artifacts/tx-os/src/hooks/use-dock-visible.ts — localStorage-backed
  preference with a custom window event for in-tab sync and the native
  `storage` event for cross-tab sync. Default = true.
- DockBody in settings-panel: single ToggleRow under a new "App dock"
  section ("settingsPanel.section.dock" / "settingsPanel.dock.show")
- AppDock now returns null when the preference is off and clears
  `--app-dock-height` so page padding doesn't stay reserved.

Code review: PASS (architect). No remaining references to the removed
infra. Typecheck shows only pre-existing errors in executive-meetings.ts
and push.ts unrelated to this change.

Follow-up: publish to Gitea + redeploy on Mac (proposed as a follow-up
task).

lib/api-spec/openapi.yaml

@@ -633,64 +633,6 @@ paths:
               schema:
                 $ref: "#/components/schemas/ErrorResponse"
 
-  /me/apps:
-    get:
-      operationId: listMyApps
-      tags: [apps]
-      summary: List apps for the current user with their per-user hidden state
-      description: |
-        Returns every globally active app (regardless of the per-user hidden
-        flag), each with a `hidden` boolean indicating whether the current
-        user has hidden it from their own Home/Dock via PUT /me/apps/{appId}/hidden.
-        Used by the per-user Settings panel; the Home and Dock continue to use
-        GET /apps which already filters out hidden apps server-side.
-      responses:
-        "200":
-          description: Apps visible to the current user, with per-user hidden state
-          content:
-            application/json:
-              schema:
-                type: array
-                items:
-                  $ref: "#/components/schemas/MyApp"
-
-  /me/apps/{appId}/hidden:
-    put:
-      operationId: updateMyAppHidden
-      tags: [apps]
-      summary: Hide or show an app for the current user
-      parameters:
-        - name: appId
-          in: path
-          required: true
-          schema:
-            type: integer
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              $ref: "#/components/schemas/UpdateMyAppHiddenBody"
-      responses:
-        "200":
-          description: Updated per-user app state
-          content:
-            application/json:
-              schema:
-                $ref: "#/components/schemas/MyApp"
-        "400":
-          description: Validation error
-          content:
-            application/json:
-              schema:
-                $ref: "#/components/schemas/ErrorResponse"
-        "404":
-          description: App not found or not visible to the current user
-          content:
-            application/json:
-              schema:
-                $ref: "#/components/schemas/ErrorResponse"
-
   # Settings
   /settings:
     get:
@@ -4289,23 +4231,6 @@ components:
           type: string
           format: date-time
 
-    MyApp:
-      allOf:
-        - $ref: "#/components/schemas/App"
-        - type: object
-          required: [hidden]
-          properties:
-            hidden:
-              type: boolean
-              description: True when the current user has hidden this app from their Home/Dock.
-
-    UpdateMyAppHiddenBody:
-      type: object
-      required: [hidden]
-      properties:
-        hidden:
-          type: boolean
-
     UpdateMyAppOrderBody:
       type: object
       required: [order]