feat: add recurring event deletion with three modes

Implement three deletion modes for recurring events:
- single: exclude specific occurrence via EXDATE mechanism
- future: set RRULE UNTIL to stop future occurrences
- all: delete entire event series

Changes include:
- Add exceptionDates field to CalendarEvent model
- Add RecurringDeleteMode type and DeleteRecurringEventDTO
- EventService.deleteRecurring() with mode-based logic using rrule library
- EventController DELETE endpoint accepts mode/occurrenceDate query params
- recurrenceExpander filters out exception dates during expansion
- AI tools support deleteMode and occurrenceDate for proposed deletions
- ChatService.confirmEvent() handles recurring delete modes
- New DeleteEventModal component for unified delete confirmation UI
- Calendar screen integrates modal for both recurring and non-recurring events

apps/server/src/app.ts

@@ -35,7 +35,10 @@ if (process.env.NODE_ENV !== "production") {
       "Access-Control-Allow-Methods",
       "GET, POST, PUT, DELETE, OPTIONS",
     );
-    res.header("Access-Control-Allow-Headers", "Content-Type, Authorization, X-User-Id");
+    res.header(
+      "Access-Control-Allow-Headers",
+      "Content-Type, Authorization, X-User-Id",
+    );
     if (req.method === "OPTIONS") {
       res.sendStatus(200);
       return;
@@ -54,8 +57,13 @@ const aiProvider = new GPTAdapter();
 
 // Initialize services
 const authService = new AuthService(userRepo);
-const chatService = new ChatService(chatRepo, eventRepo, aiProvider);
 const eventService = new EventService(eventRepo);
+const chatService = new ChatService(
+  chatRepo,
+  eventRepo,
+  eventService,
+  aiProvider,
+);
 
 // Initialize controllers
 const authController = new AuthController(authService);