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/any-promise/optional.js

@@ -0,0 +1,6 @@
+"use strict";
+try {
+  module.exports = require('./register')().Promise || null
+} catch(e) {
+  module.exports = null
+}