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/services/exam/examRepository.ts

@@ -0,0 +1,56 @@
+/**
+ * examRepository — the SINGLE module that talks to the /api/exam backend (spec R2.1 seam).
+ *
+ * All exam-marker persistence flows through here so a later dual-write / offline cache can slot
+ * in without touching feature code. Mirrors the auth pattern of timetableService: take the
+ * Supabase session JWT and send it as a Bearer token; the API enforces RLS as the user.
+ */
+import axios from 'axios';
+
+import { API_BASE } from '../../config/apiConfig';
+import { supabase } from '../../supabaseClient';
+import type {
+  CreateTemplatePayload,
+  ExamTemplate,
+  ExamTemplateDetail,
+} from '../../types/exam.types';
+
+const EXAM_BASE = `${API_BASE}/api/exam`;
+
+async function authHeaders(): Promise<Record<string, string>> {
+  const { data: { session } } = await supabase.auth.getSession();
+  if (!session?.access_token) {
+    throw new Error('No authentication token available');
+  }
+  return { Authorization: `Bearer ${session.access_token}` };
+}
+
+export const examRepository = {
+  async listTemplates(includeArchived = false): Promise<ExamTemplate[]> {
+    const headers = await authHeaders();
+    const res = await axios.get<{ templates: ExamTemplate[] }>(
+      `${EXAM_BASE}/templates`,
+      { headers, params: { include_archived: includeArchived } },
+    );
+    return res.data.templates ?? [];
+  },
+
+  async getTemplate(templateId: string): Promise<ExamTemplateDetail> {
+    const headers = await authHeaders();
+    const res = await axios.get<ExamTemplateDetail>(`${EXAM_BASE}/templates/${templateId}`, { headers });
+    return res.data;
+  },
+
+  async createTemplate(payload: CreateTemplatePayload): Promise<ExamTemplate> {
+    const headers = await authHeaders();
+    const res = await axios.post<ExamTemplate>(`${EXAM_BASE}/templates`, payload, { headers });
+    return res.data;
+  },
+
+  async archiveTemplate(templateId: string): Promise<void> {
+    const headers = await authHeaders();
+    await axios.delete(`${EXAM_BASE}/templates/${templateId}`, { headers });
+  },
+};
+
+export default examRepository;