Playground demo: OSC 9 desktop notification, OSC 9;4 taskbar/dock progress, and OSC 22 pointer shape.

These are host-terminal features, not something Raxol renders itself. Ghostty, iTerm2, WezTerm, and Windows Terminal draw the dock/taskbar progress bar from OSC 9;4; most other terminals (including many Linux emulators) silently ignore all three sequences. This demo always emits them and trusts the terminal to honor or drop them -- there is no capability detection here.