feat: Add email signature feature

- Add email_signatures table to schema
- Add email signature service, controller, routes
- Users can create/edit signature in Profile
- Toggle to include signature when sending email replies

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

src/app.js

@@ -30,6 +30,7 @@ import eventRoutes from './routes/event.routes.js';
 import messageRoutes from './routes/message.routes.js';
 import userRoutes from './routes/user.routes.js';
 import serviceRoutes from './routes/service.routes.js';
+import emailSignatureRoutes from './routes/email-signature.routes.js';
 
 const app = express();
 
@@ -126,6 +127,7 @@ app.use('/api/events', eventRoutes);
 app.use('/api/messages', messageRoutes);
 app.use('/api/users', userRoutes);
 app.use('/api/services', serviceRoutes);
+app.use('/api/email-signature', emailSignatureRoutes);
 
 // Basic route
 app.get('/', (req, res) => {