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/use-sidecar/dist/es2019/medium.d.ts

@@ -0,0 +1,3 @@
+import { MiddlewareCallback, SideCarMedium, SideCarMediumOptions, SideMedium } from './types';
+export declare function createMedium<T>(defaults?: T, middleware?: MiddlewareCallback<T>): Readonly<SideMedium<T>>;
+export declare function createSidecarMedium<T = {}>(options?: SideCarMediumOptions): Readonly<SideCarMedium<T>>;