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/_lib/getRoundingMethod.mjs

@@ -0,0 +1,8 @@
+export function getRoundingMethod(method) {
+  return (number) => {
+    const round = method ? Math[method] : Math.trunc;
+    const result = round(number);
+    // Prevent negative zero
+    return result === 0 ? 0 : result;
+  };
+}