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/nanoid/async/package.json

@@ -0,0 +1,12 @@
+{
+  "type": "module",
+  "main": "index.cjs",
+  "module": "index.js",
+  "react-native": {
+    "./index.js": "./index.native.js"
+  },
+  "browser": {
+    "./index.js": "./index.browser.js",
+    "./index.cjs": "./index.browser.cjs"
+  }
+}