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

apps/client/src/components/CustomTextInput.tsx

@@ -30,6 +30,7 @@ const CustomTextInput = (props: CustomTextInputProps) => {
       secureTextEntry={props.secureTextEntry}
       autoCapitalize={props.autoCapitalize}
       keyboardType={props.keyboardType}
+      selection={!focused ? { start: 0 } : undefined}
       style={{
         backgroundColor: theme.messageBorderBg,
         color: theme.textPrimary,