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/external.d.ts

@@ -0,0 +1,6 @@
+export * from "./errors.js";
+export * from "./helpers/parseUtil.js";
+export * from "./helpers/typeAliases.js";
+export * from "./helpers/util.js";
+export * from "./types.js";
+export * from "./ZodError.js";