Fix pro_state field name mismatch in /auth/me response

Flutter reads 'professional_state' but Prisma returns 'pro_state'.
Add professional_state alias in me() response so proState is read correctly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/auth/auth.service.ts

@@ -104,7 +104,7 @@ export class AuthService {
       },
     });
     if (!user) throw new UnauthorizedException('Usuario no encontrado');
-    return user;
+    return { ...user, professional_state: user.pro_state };
   }
 
   async getProfessionalId(userId: string): Promise<string | null> {