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/controllers/ChatController.ts

@@ -1,4 +1,5 @@
 import { Response } from 'express';
+import { SendMessageDTO } from '@caldav/shared';
 import { ChatService } from '../services';
 import { AuthenticatedRequest } from '../middleware';
 
@@ -6,15 +7,36 @@ export class ChatController {
   constructor(private chatService: ChatService) {}
 
   async sendMessage(req: AuthenticatedRequest, res: Response): Promise<void> {
-    throw new Error('Not implemented');
+    try {
+      const userId = req.user!.userId;
+      const data: SendMessageDTO = req.body;
+      const response = await this.chatService.processMessage(userId, data);
+      res.json(response);
+    } catch (error) {
+      res.status(500).json({ error: 'Failed to process message' });
+    }
   }
 
   async confirmEvent(req: AuthenticatedRequest, res: Response): Promise<void> {
-    throw new Error('Not implemented');
+    try {
+      const userId = req.user!.userId;
+      const { conversationId, messageId } = req.params;
+      const response = await this.chatService.confirmEvent(userId, conversationId, messageId);
+      res.json(response);
+    } catch (error) {
+      res.status(500).json({ error: 'Failed to confirm event' });
+    }
   }
 
   async rejectEvent(req: AuthenticatedRequest, res: Response): Promise<void> {
-    throw new Error('Not implemented');
+    try {
+      const userId = req.user!.userId;
+      const { conversationId, messageId } = req.params;
+      const response = await this.chatService.rejectEvent(userId, conversationId, messageId);
+      res.json(response);
+    } catch (error) {
+      res.status(500).json({ error: 'Failed to reject event' });
+    }
   }
 
   async getConversations(req: AuthenticatedRequest, res: Response): Promise<void> {