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

docs/component-diagram.puml

@@ -16,6 +16,8 @@ package "apps/client (Expo React Native)" as ClientPkg #87CEEB {
         [Login/Register] as AuthScreens
         [Calendar View] as CalendarScreen
         [Chat View] as ChatScreen
+        [Settings] as SettingsScreen
+        [Edit Event] as EditEventScreen
         [Event Detail] as EventDetail
         [Note Editor] as NoteScreen
     }
@@ -25,17 +27,20 @@ package "apps/client (Expo React Native)" as ClientPkg #87CEEB {
         [Auth Service] as ClientAuth
         [Event Service] as ClientEvent
         [Chat Service] as ClientChat
+        [Caldav Config Service] as ClientCaldav
     }
 
     package "Components" {
         [UI Components] as UIComponents
         [Event Cards] as EventCards
+        [Auth Guard] as AuthGuard
     }
 
     package "Stores" {
         [Auth Store] as AuthStore
         [Events Store] as EventsStore
         [Chat Store] as ChatStore
+        [Theme Store] as ThemeStore
     }
 }
 
@@ -59,10 +64,11 @@ package "apps/server (Express.js)" as ServerPkg #98FB98 {
         [AuthService] as AuthSvc
         [ChatService] as ChatSvc
         [EventService] as EventSvc
+        [CaldavService] as CaldavSvc
     }
 
     package "AI Implementations" {
-        [ClaudeAdapter] as Claude
+        [GPTAdapter] as GPT
     }
 
     package "Data Access Implementations" {
@@ -80,25 +86,35 @@ package "apps/server (Express.js)" as ServerPkg #98FB98 {
 
 ' ===== ROW 4: EXTERNAL =====
 database "MongoDB" as MongoDB
-cloud "Claude API" as ClaudeAPI
+cloud "OpenAI API" as OpenAIAPI
+cloud "CalDAV Server" as CaldavServer
 
 ' ===== CONNECTIONS =====
 
 ' Frontend: Screens -> Services
 AuthScreens --> ClientAuth
 CalendarScreen --> ClientEvent
+CalendarScreen --> ClientCaldav
 ChatScreen --> ClientChat
+SettingsScreen --> ClientCaldav
+EditEventScreen --> ClientEvent
 EventDetail --> ClientEvent
 NoteScreen --> ClientEvent
 
 ClientAuth --> ApiClient
 ClientEvent --> ApiClient
 ClientChat --> ApiClient
+ClientCaldav --> ApiClient
 
 ApiClient --> AuthStore
 ClientEvent --> EventsStore
 ClientChat --> ChatStore
 
+' Frontend: Auth
+AuthGuard --> AuthStore
+AuthGuard --> ClientCaldav
+AuthScreens --> ClientCaldav
+
 ' Frontend: Screens -> Components
 CalendarScreen --> EventCards
 ChatScreen --> EventCards
@@ -121,14 +137,20 @@ Routes --> Controllers
 Controllers --> AuthSvc
 Controllers --> ChatSvc
 Controllers --> EventSvc
+Controllers --> CaldavSvc
 
 ' Backend: Service -> Interfaces
 AuthSvc --> Interfaces
 ChatSvc --> Interfaces
 EventSvc --> Interfaces
+CaldavSvc --> Interfaces
+
+' Backend: Service dependencies
+ChatSvc --> EventSvc
+CaldavSvc --> EventSvc
 
 ' Backend: AI & Data Access implement Interfaces
-Claude ..|> Interfaces
+GPT ..|> Interfaces
 Repos ..|> Interfaces
 
 ' Backend: Service -> Utils
@@ -143,6 +165,7 @@ Repos --> Schemas
 
 ' Backend -> External
 Schemas --> MongoDB
-Claude --> ClaudeAPI
+GPT --> OpenAIAPI
+CaldavSvc --> CaldavServer
 
 @enduml