fix: Allow undefined ref for SearchBarCommands in SearchBarProps

[Pnlvfx]

Description

This change updates the type definition for SearchBarProps to accept a ref that can be undefined. Previously, the ref was forced to be non-nullable, which required developers to use workarounds (like non-null assertions) even though React handles null/undefined refs gracefully. With React 19, the framework ensures that refs are managed correctly regardless of their empty initial state.

By allowing n undefined ref, we align the type definitions with React's natural behavior and improve the developer experience by eliminating unnecessary TypeScript errors. This change has no runtime impact, as the component lifecycle guarantees that the ref will be properly set before it is used.

Example that trigger the Typescript Error below:

const searchBarRef = useRef<SearchBarCommands>(undefined);

useLayoutEffect(() => {
  navigation.setOptions({
    headerSearchBarOptions: {
      tintColor: colors.text,
      ref: searchBarRef,
    } satisfies SearchBarProps,
  });
}, [navigation, colors.text]);

Type 'RefObject<SearchBarCommands | undefined>' is not assignable to type 'RefObject'.
Type 'SearchBarCommands | undefined' is not assignable to type 'SearchBarCommands'.
Type 'undefined' is not assignable to type 'SearchBarCommands'.ts(2322)

[Pnlvfx]

Description

This change updates the type definition for SearchBarProps to accept a ref that can be undefined. Previously, the ref was forced to be non-nullable, which required developers to use workarounds (like non-null assertions) even though React handles null/undefined refs gracefully. With React 19, the framework ensures that refs are managed correctly regardless of their empty initial state.

By allowing n undefined ref, we align the type definitions with React's natural behavior and improve the developer experience by eliminating unnecessary TypeScript errors. This change has no runtime impact, as the component lifecycle guarantees that the ref will be properly set before it is used.

Example that trigger the Typescript Error below:

const searchBarRef = useRef<SearchBarCommands>(undefined); // or null

useLayoutEffect(() => {
  navigation.setOptions({
    headerSearchBarOptions: {
      tintColor: colors.text,
      ref: searchBarRef,
    } satisfies SearchBarProps,
  });
}, [navigation, colors.text]);

Type 'RefObject<SearchBarCommands | undefined>' is not assignable to type 'RefObject'. Type 'SearchBarCommands | undefined' is not assignable to type 'SearchBarCommands'. Type 'undefined' is not assignable to type 'SearchBarCommands'.ts(2322)

[Pnlvfx]

Test passed successfully.

[kkafar]

hey! thanks for the PR. I took a quick glance I'm not convinced of backward compat of your solution with react 18 yet.
I'll try to find some time this week to test this.