feat: add MyExams, MyResults, Settings, and Workspace components

- Implemented MyExams component for managing user exams, including loading, deleting, and creating new exams.
- Created MyResults component to display user results with options to review and delete results.
- Developed Settings component for updating user display name and changing password.
- Introduced Workspace component to serve as a container for MyExams, MyResults, and Settings, with navigation between tabs.

frontend/src/types.ts

@@ -68,6 +68,7 @@ export interface Question {
 }
 
 export interface Exam {
+  id?: string;
   title: string;
   subtitle?: string;
   author?: string;