implement chat messaging with event proposals

- Add functional chat with server communication and test responses
- Add ProposedEventCard component for confirm/reject actions
- Move Constants (Day, Month) from client to shared package
- Add dateHelpers utility for weekday calculations
- Extend Themes.tsx with button and text colors
- Update CLAUDE.md with current implementation status
- Add *.tsbuildinfo to .gitignore

apps/server/src/app.ts

@@ -15,6 +15,21 @@ const mongoUri = process.env.MONGODB_URI || 'mongodb://localhost:27017/caldav';
 // Middleware
 app.use(express.json());
 
+// CORS - only needed for web browser development
+// Native mobile apps don't send Origin headers and aren't affected by CORS
+if (process.env.NODE_ENV !== 'production') {
+  app.use((req, res, next) => {
+    res.header('Access-Control-Allow-Origin', '*');
+    res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
+    res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization');
+    if (req.method === 'OPTIONS') {
+      res.sendStatus(200);
+      return;
+    }
+    next();
+  });
+}
+
 // Initialize repositories
 const userRepo = new MongoUserRepository();
 const eventRepo = new MongoEventRepository();