feat: Add email field to profile edit form

- Add email input field to profile edit form
- Display current email or 'No email address set' message
- Show helpful hint when adding email for the first time
- Update backend to accept email in profile updates
- Add email uniqueness validation
- Allow users to add/update/remove email address
- Support empty string to remove email (converts to null)

Users can now add or update their email address from the profile page, enabling them to receive email notifications.

server/src/controllers/userController.ts

@@ -41,7 +41,7 @@ export class UserController {
   async updateUserProfile(req: AuthRequest, res: Response) {
     try {
       const { id } = req.params;
-      const { firstName, lastName, username } = req.body;
+      const { firstName, lastName, username, email } = req.body;
 
       // Authorization check - users can only update their own profile
       if (!req.userId) {
@@ -91,6 +91,7 @@ export class UserController {
         firstName,
         lastName,
         username,
+        email,
       });
 
       res.json(updatedProfile);

server/src/services/userService.ts

@@ -5,6 +5,7 @@ export interface UpdateUserProfileData {
   firstName?: string;
   lastName?: string;
   username?: string;
+  email?: string;
 }
 
 export interface UpdateNotificationPreferencesData {
@@ -146,12 +147,30 @@ export class UserService {
       }
     }
 
+    // Check if email is being changed and if it's already taken
+    if (data.email !== undefined) {
+      // Allow setting email to null or empty string
+      if (data.email && data.email.trim() !== '') {
+        const existingUser = await prisma.user.findFirst({
+          where: {
+            email: data.email,
+            id: { not: userId },
+          },
+        });
+
+        if (existingUser) {
+          throw new Error('Email already in use');
+        }
+      }
+    }
+
     const updatedUser = await prisma.user.update({
       where: { id: userId },
       data: {
         firstName: data.firstName,
         lastName: data.lastName,
         username: data.username,
+        email: data.email !== undefined ? (data.email.trim() === '' ? null : data.email) : undefined,
       },
       select: {
         id: true,