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

apps/client/src/components/AuthGuard.tsx

@@ -3,6 +3,7 @@ import { View, ActivityIndicator } from "react-native";
 import { Redirect } from "expo-router";
 import { useAuthStore } from "../stores";
 import { useThemeStore } from "../stores/ThemeStore";
+import { CaldavConfigService } from "../services/CaldavConfigService";
 
 type AuthGuardProps = {
   children: ReactNode;
@@ -20,7 +21,16 @@ export const AuthGuard = ({ children }: AuthGuardProps) => {
   const { isAuthenticated, isLoading, loadStoredUser } = useAuthStore();
 
   useEffect(() => {
-    loadStoredUser();
+    const init = async () => {
+      await loadStoredUser();
+      if (!useAuthStore.getState().isAuthenticated) return;
+      try {
+        await CaldavConfigService.sync();
+      } catch {
+        // No CalDAV config or sync failed — not critical
+      }
+    };
+    init();
   }, [loadStoredUser]);
 
   if (isLoading) {

apps/client/src/components/BaseButton.tsx

@@ -2,17 +2,18 @@ import { Pressable, Text } from "react-native";
 import { useThemeStore } from "../stores/ThemeStore";
 import { ReactNode } from "react";
 
-type BaseButtonProps = {
+export type BaseButtonProps = {
   children?: ReactNode;
+  className?: string;
   onPress: () => void;
   solid?: boolean;
 };
 
-const BaseButton = ({ children, onPress, solid = false }: BaseButtonProps) => {
+const BaseButton = ({ className, children, onPress, solid = false }: BaseButtonProps) => {
   const { theme } = useThemeStore();
   return (
     <Pressable
-      className="w-11/12 rounded-lg p-4 mb-4 border-4"
+      className={`rounded-lg p-4 mb-4 border-4 ${className}`}
       onPress={onPress}
       style={{
         borderColor: theme.borderPrimary,

apps/client/src/components/CustomTextInput.tsx

@@ -0,0 +1,35 @@
+import { TextInput } from "react-native";
+import { useThemeStore } from "../stores/ThemeStore";
+import { useState } from "react";
+
+export type CustomTextInputProps = {
+  text?: string;
+  focused?: boolean;
+  className?: string;
+  multiline?: boolean;
+  onValueChange?: (text: string) => void;
+};
+
+const CustomTextInput = (props: CustomTextInputProps) => {
+  const { theme } = useThemeStore();
+  const [focused, setFocused] = useState(props.focused ?? false);
+
+  return (
+    <TextInput
+      className={`border border-solid rounded-2xl px-3 py-2 h-11/12 ${props.className}`}
+      onChangeText={props.onValueChange}
+      value={props.text}
+      multiline={props.multiline}
+      style={{
+        backgroundColor: theme.messageBorderBg,
+        color: theme.textPrimary,
+        textAlignVertical: "top",
+        borderColor: focused ? theme.chatBot : theme.borderPrimary,
+      }}
+      onFocus={() => setFocused(true)}
+      onBlur={() => setFocused(false)}
+    />
+  );
+};
+
+export default CustomTextInput;