refactor: reduce CalDAV sync to login and manual sync button only

- Remove auto-login sync in AuthGuard
- Remove 10s interval sync and syncAndReload in calendar tab
- Remove lazy syncOnce pattern in ChatService AI callbacks
- Remove CaldavService dependency from ChatService constructor

apps/server/src/services/ChatService.ts

@@ -14,7 +14,6 @@ import {
 } from "@calchat/shared";
 import { ChatRepository, AIProvider } from "./interfaces";
 import { EventService } from "./EventService";
-import { CaldavService } from "./CaldavService";
 import { getWeeksOverview, getMonthOverview } from "../utils/eventFormatters";
 
 type TestResponse = {
@@ -543,7 +542,6 @@ export class ChatService {
     private chatRepo: ChatRepository,
     private eventService: EventService,
     private aiProvider: AIProvider,
-    private caldavService: CaldavService,
   ) {}
 
   async processMessage(
@@ -578,32 +576,17 @@ export class ChatService {
         limit: 20,
       });
 
-      // Lazy CalDAV sync: only sync once when the AI first accesses event data
-      let hasSynced = false;
-      const syncOnce = async () => {
-        if (hasSynced) return;
-        hasSynced = true;
-        try {
-          await this.caldavService.sync(userId);
-        } catch {
-          // CalDAV sync is not critical for AI responses
-        }
-      };
-
       response = await this.aiProvider.processMessage(data.content, {
         userId,
         conversationHistory: history,
         currentDate: new Date(),
         fetchEventsInRange: async (start, end) => {
-          await syncOnce();
           return this.eventService.getByDateRange(userId, start, end);
         },
         searchEvents: async (query) => {
-          await syncOnce();
           return this.eventService.searchByTitle(userId, query);
         },
         fetchEventById: async (eventId) => {
-          await syncOnce();
           return this.eventService.getById(eventId, userId);
         },
       });