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/dom-helpers/esm/hyphenate.js

@@ -0,0 +1,4 @@
+var rUpper = /([A-Z])/g;
+export default function hyphenate(string) {
+  return string.replace(rUpper, '-$1').toLowerCase();
+}