feat: redesign Exams List page to show submitted custom exams

- Added Custom Exams tab showing all exams from Generation page
- Displays title, module badges, duration, and status
- Added Create Exam button
- Kept Exam Sessions tab for institutional sessions
- Search filters across exams

Made-with: Cursor

node_modules/date-fns/_lib/getRoundingMethod.d.ts

@@ -0,0 +1,4 @@
+import type { RoundingMethod } from "../types.js";
+export declare function getRoundingMethod(
+  method: RoundingMethod | undefined,
+): (number: number) => number;