feat: add cross-platform desktop automation tool (macOS + Windows)

[NSIETeam]

What

Adds a new desktop_automation tool with 17 cross-platform actions for macOS and Windows.

Actions

Category	Actions
App control	launch_app, quit_app, wait_for_app
Window management	window_manager (minimize, maximize, restore, close, front, tile_left/right/top/bottom, fullscreen)
Keyboard	keyboard, type_text, hotkey
Mouse	mouse, drag, scroll
System	screenshot, clipboard, screen_info, get_active_app, list_windows, get_window_position
Scripting	run_script (AppleScript on macOS, PowerShell on Windows)

Implementation

• macOS: osascript + cliclick for keyboard/mouse, no extra dependencies beyond brew install cliclick
• Windows: Win32 API via PowerShell P/Invoke (zero external dependencies)
• Safety: dangerous actions (run_script, quit_app, drag) show confirmation warning; YOLO mode skips confirmation
• Validation: parameter validation with clear error messages

Origin

Ported from Otto project. Adapted for EasyCode:

• Removed ProcessGuard dependency, uses standard child_process.exec
• Removed DoctorService dependency, inline which cliclick check
• Same API surface and behavior

Testing

• TypeScript compiles without errors
• Unit tests (planned: parameter validation, macOS/Windows path routing)
• Integration tests on macOS (requires cliclick)
• Integration tests on Windows