feat: add visual feedback for CalDAV save & sync actions

- Show spinner + loading text while request is in progress
- Display success (green) or error (red) message, auto-clears after 3s
- Save and Sync have independent feedback rows (both visible at once)
- Fix CaldavTextInput theming and add secureTextEntry for password
- Reset CustomTextInput cursor to start when unfocused

CLAUDE.md

@@ -77,7 +77,7 @@ src/
 │   │   ├── _layout.tsx         # Tab bar configuration (themed)
 │   │   ├── chat.tsx            # Chat screen (AI conversation)
 │   │   ├── calendar.tsx        # Calendar overview
-│   │   └── settings.tsx        # Settings screen (theme switcher, logout)
+│   │   └── settings.tsx        # Settings screen (theme switcher, logout, CalDAV config with feedback)
 │   ├── editEvent.tsx           # Event edit screen (dual-mode: calendar/chat)
 │   ├── event/
 │   │   └── [id].tsx            # Event detail screen (dynamic route)
@@ -612,7 +612,7 @@ NODE_ENV=development        # development = pretty logs, production = JSON
   - `ThemeStore`: Zustand store with theme state and setTheme()
   - `Themes.tsx`: THEMES object with defaultLight/defaultDark variants
   - All components use `useThemeStore()` for reactive theme colors
-  - Settings screen with theme switcher (light/dark) and CalDAV configuration (url, username, password with save/sync buttons, loads existing config on mount)
+  - Settings screen with theme switcher (light/dark) and CalDAV configuration (url, username, password with save/sync buttons, loads existing config on mount). Save/Sync buttons show independent feedback via `FeedbackRow` component: spinner + loading text during request, then success (green) or error (red) message that auto-clears after 3s. Both feedbacks can be visible simultaneously.
   - `BaseButton`: Reusable themed button component
 - Tab navigation (Chat, Calendar, Settings) implemented with themed UI
 - Calendar screen fully functional:
@@ -639,7 +639,7 @@ NODE_ENV=development        # development = pretty logs, production = JSON
 - `EventService`: getAll(), getById(), getByDateRange(), create(), update(), delete(mode, occurrenceDate) - fully implemented with recurring delete modes
 - `ChatService`: sendMessage(), confirmEvent(deleteMode, occurrenceDate), rejectEvent(), getConversations(), getConversation(), updateProposalEvent() - fully implemented with cursor pagination, recurring delete support, and proposal editing
 - `CaldavConfigService`: saveConfig(), getConfig(), deleteConfig(), pull(), pushAll(), sync() - CalDAV config management and sync trigger
-- `CustomTextInput`: Themed text input with focus border highlight. Props: `text`, `onValueChange`, `placeholder`, `placeholderTextColor`, `secureTextEntry`, `autoCapitalize`, `keyboardType`, `className`, `multiline`. No default padding — callers must set padding via `className` (e.g., `px-3 py-2` or `p-4`)
+- `CustomTextInput`: Themed text input with focus border highlight. Props: `text`, `onValueChange`, `placeholder`, `placeholderTextColor`, `secureTextEntry`, `autoCapitalize`, `keyboardType`, `className`, `multiline`. No default padding — callers must set padding via `className` (e.g., `px-3 py-2` or `p-4`). When not focused, cursor is reset to start (`selection={{ start: 0 }}`) to avoid text appearing scrolled to the end.
 - `CardBase`: Reusable card component with header (title/subtitle), content area, and optional footer button - configurable padding, border, text size via props, ScrollView uses `nestedScrollEnabled` for Android
 - `ModalBase`: Reusable modal wrapper with backdrop (absolute-positioned behind card), uses CardBase internally - provides click-outside-to-close, Android back button support, and proper scrolling on Android
 - `EventCardBase`: Event card with date/time/recurring icons - uses CardBase for structure. Accepts `recurrenceRule` string (not boolean) and displays German-formatted recurrence via `formatRecurrenceRule()`