[Hooks] Implement Native OS Integration Hooks (File/Folder Dialogs & Clipboard)

[rorychatt]

Problem Statement

Applications built with rusty targeting native desktop environments require reactive hooks for invoking native OS dialogs and interacting with the system clipboard (use_file_dialog, use_folder_dialog, use_save_dialog, use_clipboard).

Missing Functionality

• use_file_dialog: Hook to prompt native file open picker with file filters.
• use_folder_dialog: Hook to prompt native directory/folder picker.
• use_save_dialog: Hook to prompt native save file picker with default names and extensions.
• use_clipboard: Asynchronous read/write hook for system clipboard text and data.

Proposed Architecture & Design

1. Implement hooks in rusty/src/hooks/os.rs.
2. For native desktop targets, delegate to rfd (Rust Native File Dialogs) and arboard (clipboard).
3. For WebAssembly / browser targets, fallback to HTML5 Input/File API and navigator.clipboard.

Acceptance Criteria

• use_file_dialog, use_folder_dialog, use_save_dialog trigger native file selection pickers on desktop targets.
• use_clipboard provides reactive copy and paste operations across platforms.
• Fallback behavior handles web browser environments gracefully.