useKeyboard keyboardShown wrong value

[Ainias]

When a component uses useKeyboard() and this component is mounted while the keyboard is open, useKeyboard().keyboardShown returns false.

The background is we have a sticky button at the bottom on multiple screens. This button should not be displayed when the keyboard is open, since it takes away too much space. In one of those screens we only show the button after an text-input is made. At this point the keyboard is open and the button is shown because of the error above.

[jforaker]

On Ipad, in split screen, keyboardHeight retains its value when keyboard is dismissed.

This is easy replicable.

Steps:

1. do split screen
2. open keyboard
3. close keyboard
4. see keyboardHeight does not set to 0

const { keyboardHeight } = useKeyboard();
console.log('keyboardHeight: ', keyboardHeight);

keyboardHeight:  422

[huytdps13400]

Fix PR is open: #430.

It initializes useKeyboard from Keyboard.isVisible() and Keyboard.metrics() when available, with optional calls so the package remains runtime-compatible with its RN >=0.70 peer range. It also clears keyboardHeight for every hide event, including the coordinate-bearing iPad split-screen case reported above.

The regression produced three failures before the fix and now passes with the full 45-test suite, typecheck, lint, and formatting.