1. Clipboard paste (rdp_send_clipboard): simulates typing each character
via scancode key press/release events. Full ASCII coverage including
all symbols, numbers, and shifted characters. Handles 32-char
generated passwords without manual typing.
2. Keyboard grab defaults to ON so RDP sessions accept keyboard input
immediately without requiring the user to click the toolbar toggle.
3. Frame dirty flag: GraphicsUpdate sets an AtomicBool, get_frame only
encodes + returns base64 when dirty (returns empty string otherwise).
Eliminates ~8MB/frame base64 encoding on unchanged frames at 30fps.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>