feat: add CalDAV synchronization with automatic sync

- Add CaldavService with tsdav/ical.js for CalDAV server communication
- Add CaldavController, CaldavRepository, and caldav routes
- Add client-side CaldavConfigService with sync(), config CRUD
- Add CalDAV settings UI with config load/save in settings screen
- Sync on login, auto-login (AuthGuard), periodic timer (calendar), and sync button
- Push single events to CalDAV on server-side create/update/delete
- Push all events to CalDAV after chat event confirmation
- Refactor ChatService to use EventService instead of direct EventRepository
- Rename CalDav/calDav to Caldav/caldav for consistent naming
- Add Radicale Docker setup for local CalDAV testing
- Update PlantUML diagrams and CLAUDE.md with CalDAV architecture

packages/shared/src/models/CaldavConfig.ts

@@ -0,0 +1,7 @@
+export interface CaldavConfig {
+  userId: string;
+  serverUrl: string;
+  username: string;
+  password: string;
+  syncIntervalSeconds?: number;
+}

packages/shared/src/models/CalendarEvent.ts

@@ -1,6 +1,8 @@
 export interface CalendarEvent {
   id: string;
   userId: string;
+  caldavUUID?: string;
+  etag?: string;
   title: string;
   description?: string;
   startTime: Date;
@@ -10,9 +12,11 @@ export interface CalendarEvent {
   exceptionDates?: string[]; // ISO date strings (YYYY-MM-DD) for excluded occurrences
   createdAt?: Date;
   updatedAt?: Date;
+  caldavSyncStatus?: CaldavSyncStatus;
 }
 
 export type RecurringDeleteMode = "single" | "future" | "all";
+export type CaldavSyncStatus = "synced" | "error";
 
 export interface DeleteRecurringEventDTO {
   mode: RecurringDeleteMode;
@@ -20,6 +24,8 @@ export interface DeleteRecurringEventDTO {
 }
 
 export interface CreateEventDTO {
+  caldavUUID?: string;
+  etag?: string;
   title: string;
   description?: string;
   startTime: Date;
@@ -27,9 +33,12 @@ export interface CreateEventDTO {
   note?: string;
   recurrenceRule?: string;
   exceptionDates?: string[]; // For display in proposals
+  caldavSyncStatus?: CaldavSyncStatus;
 }
 
 export interface UpdateEventDTO {
+  caldavUUID?: string;
+  etag?: string;
   title?: string;
   description?: string;
   startTime?: Date;
@@ -37,6 +46,7 @@ export interface UpdateEventDTO {
   note?: string;
   recurrenceRule?: string;
   exceptionDates?: string[];
+  caldavSyncStatus?: CaldavSyncStatus;
 }
 
 export interface ExpandedEvent extends CalendarEvent {

packages/shared/src/models/index.ts

@@ -2,3 +2,4 @@ export * from "./User";
 export * from "./CalendarEvent";
 export * from "./ChatMessage";
 export * from "./Constants";
+export * from "./CaldavConfig";

packages/shared/src/utils/formatters.ts

@@ -69,3 +69,11 @@ export function formatDateWithWeekdayShort(date: Date): string {
     month: "2-digit",
   });
 }
+
+// Format date as YYYY-MM-DD for exception date comparison
+export function formatDateKey(date: Date): string {
+  const year = date.getFullYear();
+  const month = String(date.getMonth() + 1).padStart(2, "0");
+  const day = String(date.getDate()).padStart(2, "0");
+  return `${year}-${month}-${day}`;
+}