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/architecture-class-diagram.puml

@@ -30,6 +30,8 @@ package "Controller Layer" #ADD8E6 {
     }
 
     class EventController {
+        ' -pushToCaldav()
+        ' -deleteFromCaldav()
         ' +create()
         ' +getById()
         ' +getAll()
@@ -38,6 +40,15 @@ package "Controller Layer" #ADD8E6 {
         ' +delete()
     }
 
+    class CaldavController {
+        ' +saveConfig()
+        ' +loadConfig()
+        ' +deleteConfig()
+        ' +pullEvents()
+        ' +pushEvents()
+        ' +pushEvent()
+    }
+
     class AuthMiddleware {
         ' +authenticate()
     }
@@ -59,9 +70,12 @@ package "Service Layer" #90EE90 {
             ' +findById()
             ' +findByUserId()
             ' +findByDateRange()
+            ' +findByCaldavUUID()
+            ' +searchByTitle()
             ' +create()
             ' +update()
             ' +delete()
+            ' +addExceptionDate()
         }
 
         interface ChatRepository {
@@ -69,6 +83,14 @@ package "Service Layer" #90EE90 {
             ' +createConversation()
             ' +getMessages()
             ' +createMessage()
+            ' +updateProposalResponse()
+            ' +updateProposalEvent()
+        }
+
+        interface CaldavRepository {
+            ' +findByUserId()
+            ' +createOrUpdate()
+            ' +deleteByUserId()
         }
     }
 
@@ -80,7 +102,7 @@ package "Service Layer" #90EE90 {
 
     class ChatService {
         ' -chatRepo: ChatRepository
-        ' -eventRepo: EventRepository
+        ' -eventService: EventService
         ' -aiProvider: AIProvider
         ' +processMessage()
         ' +confirmEvent()
@@ -95,13 +117,29 @@ package "Service Layer" #90EE90 {
         ' +getById()
         ' +getAll()
         ' +getByDateRange()
+        ' +searchByTitle()
+        ' +findByCaldavUUID()
         ' +update()
         ' +delete()
+        ' +deleteRecurring()
+    }
+
+    class CaldavService {
+        ' -caldavRepo: CaldavRepository
+        ' -eventService: EventService
+        ' +connect()
+        ' +pullEvents()
+        ' +pushEvent()
+        ' +pushAll()
+        ' +deleteEvent()
+        ' +getConfig()
+        ' +saveConfig()
+        ' +deleteConfig()
     }
 }
 
 package "AI Implementations" #FFA07A {
-    class ClaudeAdapter implements AIProvider {
+    class GPTAdapter implements AIProvider {
         ' -apiKey: string
         ' +processMessage()
     }
@@ -119,6 +157,10 @@ package "Data Access Implementations" #FFD700 {
     class MongoChatRepository implements ChatRepository {
         ' -model: ChatModel
     }
+
+    class MongoCaldavRepository implements CaldavRepository {
+        ' -model: CaldavConfigModel
+    }
 }
 
 package "Models" #D3D3D3 {
@@ -169,15 +211,20 @@ package "Utils" #DDA0DD {
 ' Controller -> Service
 AuthController --> AuthService
 ChatController --> ChatService
+ChatController --> CaldavService
 EventController --> EventService
+EventController --> CaldavService
+CaldavController --> CaldavService
 AuthMiddleware --> JWT
 
 ' Service -> Interfaces (intern)
 AuthService --> UserRepository
 ChatService --> ChatRepository
-ChatService --> EventRepository
+ChatService --> EventService
 ChatService --> AIProvider
 EventService --> EventRepository
+CaldavService --> CaldavRepository
+CaldavService --> EventService
 
 ' Auth uses Utils
 AuthService --> JWT