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/zod/v3/errors.d.cts

@@ -0,0 +1,5 @@
+import type { ZodErrorMap } from "./ZodError.cjs";
+import defaultErrorMap from "./locales/en.cjs";
+export { defaultErrorMap };
+export declare function setErrorMap(map: ZodErrorMap): void;
+export declare function getErrorMap(): ZodErrorMap;