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/types/exam.types.ts

@@ -0,0 +1,78 @@
+/**
+ * Exam-marker types — mirror the FastAPI /api/exam contract (see api routers/exam/schemas.py).
+ * Supabase is source of truth for this operational data; the graph (cc.public.exams) joins by
+ * the shared UUIDs (template/question/region ids, exam_code).
+ */
+
+export type ExamTemplateStatus = 'draft' | 'ready' | 'archived';
+
+export interface ExamTemplate {
+  id: string;
+  title: string;
+  subject: string | null;
+  exam_id: string | null;
+  exam_code: string | null;
+  source_file_id: string | null;
+  page_count: number | null;
+  institute_id: string;
+  teacher_id: string;
+  status: ExamTemplateStatus;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface CreateTemplatePayload {
+  title: string;
+  subject?: string;
+  exam_id?: string;
+  exam_code?: string;
+  source_file_id?: string;
+  page_count?: number;
+  institute_id?: string;
+}
+
+/** Canvas children (used from S4-9 onward; defined here so the seam is complete). */
+export interface ExamQuestion {
+  id: string;
+  template_id: string;
+  parent_id: string | null;
+  label: string;
+  order: number;
+  max_marks: number;
+  answer_type: string | null;
+  mcq_options: unknown | null;
+  mark_scheme: Record<string, unknown>;
+  is_container: boolean;
+  spec_ref: string | null;
+}
+
+export interface ExamResponseArea {
+  id: string;
+  question_id: string;
+  template_id: string;
+  page: number;
+  bounds: Record<string, number>;
+  kind: 'response' | 'context';
+  response_form: string | null;
+  source: 'manual' | 'ai';
+  confirmed: boolean;
+  confidence: number | null;
+}
+
+export interface ExamBoundary {
+  id: string;
+  template_id: string;
+  question_id: string | null;
+  label: string | null;
+  page_index: number;
+  y: number;
+  bounds: Record<string, number> | null;
+  source: 'manual' | 'ai';
+  confirmed: boolean;
+}
+
+export interface ExamTemplateDetail extends ExamTemplate {
+  questions: ExamQuestion[];
+  response_areas: ExamResponseArea[];
+  boundaries: ExamBoundary[];
+}