Add HighlightText component for search result highlighting in PostCard.
Refactor QRCodeScanner to use async permission methods with better error
handling. Improve SearchScreen with stable function refs and pass
highlightKeyword to PostCard. Modernize MessageListScreen search UI with
SearchBar and TabBar components. Add emoji virtualization to EmojiPanel
and auto-focus input after inserting emoji.
BREAKING CHANGE: EmojiPanel onFocusInput prop added for focus management
