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/next-themes/dist/index.d.mts

@@ -0,0 +1,7 @@
+import * as React from 'react';
+import { UseThemeProps, ThemeProviderProps } from './types.mjs';
+
+declare const useTheme: () => UseThemeProps;
+declare const ThemeProvider: (props: ThemeProviderProps) => string | number | boolean | Iterable<React.ReactNode> | React.JSX.Element;
+
+export { ThemeProvider, useTheme };