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/react-style-singleton/dist/es2019/component.d.ts

@@ -0,0 +1,21 @@
+import * as React from 'react';
+declare type Props = {
+    /**
+     * styles to apply
+     */
+    styles: string;
+    /**
+     * marks style as dynamic, so it will be reapplied on styles change
+     * note: this is not expected behavior from a "singleton"
+     * @default false
+     */
+    dynamic?: boolean;
+};
+/**
+ * create a Component to add styles on demand
+ * - styles are added when first instance is mounted
+ * - styles are removed when the last instance is unmounted
+ * - changing styles in runtime does nothing unless dynamic is set. But with multiple components that can lead to the undefined behavior
+ */
+export declare const styleSingleton: () => React.FC<Props>;
+export {};