fix(mobile): fixing mnemonics screen behavior [PERA-3698]

[fmsouza]

Pull Request Template

Description

• Fixed focus bouncing between mnemonic input fields by replacing a fragile setTimeout-based focus transfer with a useEffect that fires after render commit when refs are guaranteed to be set
• Fixed autocomplete suggestions not filling the field — the dropdown was absolutely positioned inside a small parent view, so on iOS taps fell through to the TextInput row underneath instead of hitting the suggestion. Moved the dropdown to render inline in the layout flow so it properly receives touches
• Eliminated stale closure in paste detection — handleWordChange now reads from a wordsRef instead of capturing words in its dependency array, preventing false clipboard checks on rapid typing
• Stabilized input refs — replaced per-render inline ref callbacks (24/25 new functions every render) with a useMemo-based refCallbacks array created once
• Added deps to useImperativeHandle in PWInput to prevent unnecessary handle recreation each render
• All fixes apply to both 24-word (HD wallet) and 25-word (Algo25) mnemonic flows

Related Issues

• closes https://algorandfoundation.atlassian.net/browse/PERA-3698

Checklist

• Have you tested your changes locally?
• Have you reviewed the code for any potential issues?
• Have you documented any necessary changes in the project's documentation?
• Have you added any necessary tests for your changes?
• Have you updated any relevant dependencies?

Additional Notes

• Add any additional notes or comments that may be helpful for reviewers.