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/@radix-ui/react-use-rect/dist/index.d.ts

@@ -0,0 +1,9 @@
+import { Measurable } from '@radix-ui/rect';
+
+/**
+ * Use this custom hook to get access to an element's rect (getBoundingClientRect)
+ * and observe it along time.
+ */
+declare function useRect(measurable: Measurable | null): DOMRect | undefined;
+
+export { useRect };