feat(exam): Assessment dashboard + /exam-marker route; remove old CCExamMarker (S4-8)

- New examRepository (R2.1 seam): the only module talking to /api/exam (Supabase
  JWT → Bearer, axios to API_BASE). list/get/create/archive templates.
- ExamDashboardPage (/exam-marker): lists institute templates, create dialog,
  archive; cards link to setup (S4-9). Wrapped in ErrorBoundary (R6.4).
- exam.types.ts mirrors the API contract.
- Dashboard 'Exam Marker' quick action (top-level discovery, R1.3/R6.1).
  Note: the in-canvas TeacherNavigation is unsuitable for a nav section (it's
  the worker prev/next tab bar) — flagged; used the dashboard entry instead.
- R1.1 removal: deleted src/pages/tldraw/CCExamMarker/ (old 3-PDF viewer) and
  the now-dead CCExamMarkerPanel + its wiring in CCPanel/BasePanel (examMarkerProps
  was only ever passed by the deleted page).
- Fixed pre-existing broken AppRoutes test (missing TimetableListPage mock export).

Build green (vite); AppRoutes route tests pass; typecheck clean for new files.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/AppRoutes.admin.test.tsx

@@ -31,7 +31,7 @@ vi.mock('./pages/NotFoundPublic', () => ({ default: () => <div>Public Not Found<
 vi.mock('./pages/tldraw/TLDrawCanvas', () => ({ default: () => <div>Public Home</div> }));
 vi.mock('./pages/tldraw/singlePlayerPage', () => ({ default: () => <div>Single Player</div> }));
 vi.mock('./pages/tldraw/multiplayerUser', () => ({ default: () => <div>Multiplayer</div> }));
-vi.mock('./pages/tldraw/CCExamMarker/CCExamMarker', () => ({ CCExamMarker: () => <div>Exam Marker</div> }));
+vi.mock('./pages/exam', () => ({ ExamDashboardPage: () => <div>Exam Marker</div> }));
 vi.mock('./pages/user/calendarPage', () => ({ default: () => <div>Calendar</div> }));
 vi.mock('./pages/user/settingsPage', () => ({ default: () => <div>Settings</div> }));
 vi.mock('./pages/tldraw/devPlayerPage', () => ({ default: () => <div>TLDraw Dev</div> }));
@@ -46,6 +46,7 @@ vi.mock('./pages/tldraw/CCDocumentIntelligence/CCDocumentIntelligence', () => ({
 }));
 vi.mock('./pages/timetable', () => ({
   TimetablePage: () => <div>Timetable</div>,
+  TimetableListPage: () => <div>Timetable List</div>,
   ClassesPage: () => <div>Classes</div>,
   LessonPage: () => <div>Lesson</div>,
   TaughtLessonsPage: () => <div>Taught Lessons</div>,