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.

backend/src/routes/auth.ts

@@ -266,4 +266,68 @@ router.get('/me', requireAuth, (req, res) => {
   })
 })
 
+// ─── Update Current User ─────────────────────────────────
+router.patch('/me', requireAuth, (req, res) => {
+  try {
+    const { displayName } = req.body
+
+    if (typeof displayName !== 'string' || displayName.trim().length < 1 || displayName.length > 100) {
+      res.status(400).json({ error: 'Display name is required (max 100 characters)' })
+      return
+    }
+
+    const db = getDb()
+    db.prepare(`
+      UPDATE users SET display_name = ?, updated_at = unixepoch() WHERE id = ?
+    `).run(displayName.trim(), req.user!.userId)
+
+    res.json({ message: 'Profile updated successfully' })
+  } catch (err) {
+    console.error('Update profile error:', err)
+    res.status(500).json({ error: 'Internal server error' })
+  }
+})
+
+// ─── Change Password ─────────────────────────────────────
+router.post('/change-password', requireAuth, async (req, res) => {
+  try {
+    const { currentPassword, newPassword } = req.body
+
+    if (!currentPassword || !newPassword) {
+      res.status(400).json({ error: 'Current password and new password are required' })
+      return
+    }
+    if (typeof newPassword !== 'string' || newPassword.length < 8) {
+      res.status(400).json({ error: 'New password must be at least 8 characters' })
+      return
+    }
+
+    const db = getDb()
+    const user = db.prepare('SELECT password_hash FROM users WHERE id = ?').get(
+      req.user!.userId
+    ) as Record<string, unknown> | undefined
+
+    if (!user) {
+      res.status(404).json({ error: 'User not found' })
+      return
+    }
+
+    const valid = await bcrypt.compare(currentPassword as string, user['password_hash'] as string)
+    if (!valid) {
+      res.status(401).json({ error: 'Current password is incorrect' })
+      return
+    }
+
+    const passwordHash = await bcrypt.hash(newPassword, BCRYPT_ROUNDS)
+    db.prepare(`
+      UPDATE users SET password_hash = ?, updated_at = unixepoch() WHERE id = ?
+    `).run(passwordHash, req.user!.userId)
+
+    res.json({ message: 'Password changed successfully' })
+  } catch (err) {
+    console.error('Change password error:', err)
+    res.status(500).json({ error: 'Internal server error' })
+  }
+})
+
 export default router

backend/src/routes/exams.ts

@@ -76,6 +76,35 @@ router.post('/', requireAuth, (req, res) => {
   }
 })
 
+// ─── Update Exam ─────────────────────────────────────────
+router.put('/:id', requireAuth, (req, res) => {
+  try {
+    const { exam } = req.body
+
+    if (!exam || !exam.title || !exam.questions?.length) {
+      res.status(400).json({ error: 'Valid exam data with title and questions is required' })
+      return
+    }
+
+    const db = getDb()
+    const result = db.prepare(`
+      UPDATE saved_exams
+      SET title = ?, subtitle = ?, exam_json = ?, updated_at = unixepoch()
+      WHERE id = ? AND user_id = ?
+    `).run(exam.title, exam.subtitle ?? null, JSON.stringify(exam), Number(req.params['id']), req.user!.userId)
+
+    if (result.changes === 0) {
+      res.status(404).json({ error: 'Exam not found' })
+      return
+    }
+
+    res.json({ message: 'Exam updated successfully' })
+  } catch (err) {
+    console.error('Update exam error:', err)
+    res.status(500).json({ error: 'Internal server error' })
+  }
+})
+
 // ─── Delete Exam ─────────────────────────────────────────
 router.delete('/:id', requireAuth, (req, res) => {
   try {