refactor: use CustomTextInput in login and register screens

- Replace raw TextInput with CustomTextInput in login and register
  for consistent focus border effect across the app
- Add placeholder, secureTextEntry, autoCapitalize, keyboardType
  props to CustomTextInput
- Remove hardcoded default padding (px-3 py-2) and h-11/12 from
  CustomTextInput, callers now set padding via className
- Add explicit px-3 py-2 to existing callers (settings, editEvent)
- Update CLAUDE.md with new CustomTextInput usage and props

apps/client/src/app/editEvent.tsx

@@ -43,7 +43,7 @@ const EditEventTextField = (props: EditEventTextFieldProps) => {
         {props.titel}
       </Text>
       <CustomTextInput
-        className="flex-1"
+        className="flex-1 px-3 py-2"
         text={props.text}
         multiline={props.multiline}
         onValueChange={props.onValueChange}