refactor: fix remaining P2 architecture issues

Fix P2-6: proxy.ts now uses Permissions constants instead of hardcoded strings

Fix P2-7: useA11yId file no longer exists (use-aria-live.ts already in hooks/)

Fix P2-8: schema.ts section numbering reordered to continuous 1-24

Fix P2-11: announcements dead code void wasPublished already removed

Fix P2-17: app-sidebar.tsx uses hasRole() instead of permission-based role inference

Fix P2-18: scheduling/actions.ts removes trailing re-export of data-access; 4 pages now import directly from data-access

Sync architecture docs 004 and 005

src/modules/scheduling/actions.ts

@@ -15,8 +15,6 @@ import {
   createScheduleChange,
   updateScheduleChangeStatus,
   getClassConflicts,
-  getAdminClassesForScheduling,
-  getTeachersForScheduling,
   getClassroomsForScheduling,
   getClassSubjectsForScheduling,
   replaceClassSchedule,
@@ -280,13 +278,3 @@ export async function getClassConflictsAction(
     return { success: false, message: "Unexpected error" }
   }
 }
-
-// Re-export data-access for server pages
-export {
-  getSchedulingRules,
-  getScheduleChanges,
-  getClassConflicts,
-  getAdminClassesForScheduling,
-  getTeachersForScheduling,
-  getClassroomsForScheduling,
-}