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/startOfToday.d.ts

@@ -0,0 +1,17 @@
+/**
+ * @name startOfToday
+ * @category Day Helpers
+ * @summary Return the start of today.
+ * @pure false
+ *
+ * @description
+ * Return the start of today.
+ *
+ * @returns The start of today
+ *
+ * @example
+ * // If today is 6 October 2014:
+ * const result = startOfToday()
+ * //=> Mon Oct 6 2014 00:00:00
+ */
+export declare function startOfToday(): Date;