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

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

docs/frontend-class-diagram.puml

@@ -22,18 +22,26 @@ package "Screens" #87CEEB {
     class RegisterScreen
     class CalendarScreen
     class ChatScreen
+    class SettingsScreen
+    class EditEventScreen
     class EventDetailScreen
     class NoteScreen
 }
 
 ' ===== COMPONENTS =====
 package "Components" #FFA07A  {
+    class AuthGuard
     class BaseBackground
     class Header
+    class BaseButton
+    class CardBase
+    class ModalBase
     class EventCardBase
     class EventCard
     class ProposedEventCard
-    class EventConfirmDialog
+    class DeleteEventModal
+    class ChatBubble
+    class TypingIndicator
 }
 
 ' ===== SERVICES =====
@@ -64,6 +72,13 @@ package "Services" #90EE90 {
         +rejectEvent()
         +getConversations()
         +getConversation()
+        +updateProposalEvent()
+    }
+    class CaldavConfigService {
+        +getConfig()
+        +saveConfig()
+        +deleteConfig()
+        +sync()
     }
 }
 
@@ -71,11 +86,10 @@ package "Services" #90EE90 {
 package "Stores" #FFD700 {
     class AuthStore {
         ' +user
-        ' +token
         ' +isAuthenticated
         ' +login()
         ' +logout()
-        ' +setToken()
+        ' +loadStoredUser()
     }
     class EventsStore {
         ' +events
@@ -86,10 +100,16 @@ package "Stores" #FFD700 {
     }
     class ChatStore {
         ' +messages
+        ' +isWaitingForResponse
         ' +addMessage()
+        ' +addMessages()
         ' +updateMessage()
         ' +clearMessages()
     }
+    class ThemeStore {
+        ' +theme
+        ' +setTheme()
+    }
 }
 
 ' ===== MODELS =====
@@ -97,6 +117,7 @@ package "Models (shared)" #D3D3D3 {
     class User
     class CalendarEvent
     class ChatMessage
+    class CaldavConfig
 }
 
 ' ===== RELATIONSHIPS =====
@@ -104,24 +125,39 @@ package "Models (shared)" #D3D3D3 {
 ' Screens -> Services
 LoginScreen --> AuthService
 CalendarScreen --> EventService
+CalendarScreen --> CaldavConfigService
 ChatScreen --> ChatService
 NoteScreen --> EventService
+EditEventScreen --> EventService
+EditEventScreen --> ChatService
+SettingsScreen --> CaldavConfigService
 
 ' Screens -> Components
 CalendarScreen --> EventCard
 ChatScreen --> ProposedEventCard
-ChatScreen --> EventConfirmDialog
+ChatScreen --> ChatBubble
+ChatScreen --> TypingIndicator
 EventCard --> EventCardBase
 ProposedEventCard --> EventCardBase
+EventCardBase --> CardBase
+ModalBase --> CardBase
+DeleteEventModal --> ModalBase
+
+' Auth
+AuthGuard --> AuthStore
+AuthGuard --> CaldavConfigService
+LoginScreen --> CaldavConfigService
 
 ' Services -> ApiClient
 AuthService --> ApiClient
 EventService --> ApiClient
 ChatService --> ApiClient
+CaldavConfigService --> ApiClient
 
 ' Services/Screens -> Stores
 AuthService --> AuthStore
-EventService --> EventsStore
+CalendarScreen --> EventsStore
 ChatScreen --> ChatStore
+SettingsScreen --> ThemeStore
 
 @enduml