fix: user registration with email support

backend/services/userService.ts

@@ -41,6 +41,15 @@ export const UserService = {
     });
   },
 
+  /**
+   * Get user by email
+   */
+  async getUserByEmail(email: string) {
+    return prisma.user.findUnique({
+      where: { email }
+    });
+  },
+
   /**
    * Create a new user with hashed password
    */
@@ -54,6 +63,7 @@ export const UserService = {
       data: {
         username,
         password: hashedPassword,
+        email,
         avatarUrl,
         role: 'CREATOR',
         status: 'ACTIVE'