feat(ui): remove window decorations and implement escape/outside-click close behavior

Remove Windows default window decorations (title bar, minimize/maximize/close buttons) for a cleaner, custom UI.

Replace default behavior with custom close/minimize logic:

• Pressing ESC in any BindKit window (context menu, settings dialog) should close/minimize that window back to the tray
• Clicking outside any BindKit window should close/minimize it back to the tray
• Settings window should follow the same behavior as the context menu

This will give the application a more modern, custom appearance consistent with the tray-based design pattern.

Affected Components:

• gui/tray_manager.py
• gui/settings_dialog.py
• Any other UI windows