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/utils/tldraw/ui-overrides/components/CCPanel.tsx

@@ -1,18 +1,15 @@
 import React, { useState } from 'react';
 import { BasePanel } from './shared/BasePanel';
-import { CCExamMarkerPanel } from './shared/CCExamMarkerPanel';
 import { BaseContext, ViewContext } from '../../../../types/navigation';
 
 interface CCPanelProps {
-  examMarkerProps?: React.ComponentProps<typeof CCExamMarkerPanel>;
   isExpanded?: boolean;
   isPinned?: boolean;
   onExpandedChange?: (expanded: boolean) => void;
   onPinnedChange?: (pinned: boolean) => void;
 }
 
-export const CCPanel: React.FC<CCPanelProps> = ({ 
-  examMarkerProps,
+export const CCPanel: React.FC<CCPanelProps> = ({
   isExpanded,
   isPinned,
   onExpandedChange,
@@ -31,8 +28,7 @@ export const CCPanel: React.FC<CCPanelProps> = ({
   };
 
   return (
-    <BasePanel 
-      examMarkerProps={examMarkerProps}
+    <BasePanel
       isExpanded={isExpanded}
       isPinned={isPinned}
       onExpandedChange={handleExpandedChange}