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/client/src/services/ChatService.ts

@@ -4,26 +4,26 @@ import {
   ChatMessage,
   ConversationSummary,
   GetMessagesOptions,
-  CalendarEvent,
-} from '@caldav/shared';
+} from "@caldav/shared";
+import { ApiClient } from "./ApiClient";
 
 export const ChatService = {
-  sendMessage: async (_data: SendMessageDTO): Promise<ChatResponse> => {
-    throw new Error('Not implemented');
+  sendMessage: async (data: SendMessageDTO): Promise<ChatResponse> => {
+    return ApiClient.post<ChatResponse>("/chat/message", data);
   },
 
   confirmEvent: async (
-    _conversationId: string,
-    _messageId: string
-  ): Promise<CalendarEvent> => {
-    throw new Error('Not implemented');
+    conversationId: string,
+    messageId: string
+  ): Promise<ChatResponse> => {
+    return ApiClient.post<ChatResponse>(`/chat/confirm/${conversationId}/${messageId}`);
   },
 
   rejectEvent: async (
-    _conversationId: string,
-    _messageId: string
-  ): Promise<void> => {
-    throw new Error('Not implemented');
+    conversationId: string,
+    messageId: string
+  ): Promise<ChatResponse> => {
+    return ApiClient.post<ChatResponse>(`/chat/reject/${conversationId}/${messageId}`);
   },
 
   getConversations: async (): Promise<ConversationSummary[]> => {