Display user's name instead of email in profile button

- Add name field to auth login/register responses
- Update User interface in AuthContext to include name
- Show name (or email as fallback) in navbar dropdown

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/routes/auth.ts

@@ -69,6 +69,7 @@ router.post('/register', async (req: Request, res: Response) => {
       user: {
         id: user.id,
         email: user.email,
+        name: user.name || null,
       },
     });
   } catch (error) {
@@ -107,6 +108,7 @@ router.post('/login', async (req: Request, res: Response) => {
       user: {
         id: user.id,
         email: user.email,
+        name: user.name || null,
       },
     });
   } catch (error) {

frontend/src/components/Layout.tsx

@@ -262,9 +262,9 @@ export default function Layout({ children }: LayoutProps) {
                   onClick={() => setIsDropdownOpen(!isDropdownOpen)}
                 >
                   <span className="user-dropdown-avatar">
-                    {user.email.charAt(0).toUpperCase()}
+                    {(user.name || user.email).charAt(0).toUpperCase()}
                   </span>
-                  <span className="user-dropdown-email">{user.email}</span>
+                  <span className="user-dropdown-email">{user.name || user.email}</span>
                   <svg
                     className="user-dropdown-arrow"
                     width="12"

frontend/src/context/AuthContext.tsx

@@ -10,6 +10,7 @@ import { authApi } from '../api/client';
 interface User {
   id: number;
   email: string;
+  name: string | null;
 }
 
 interface AuthContextType {