Add image for OpenClaw Voice Agent in README

Add LICENSE file and update .gitignore

Adjust LED rainbow animation timing for smoother transitions

Update LEDManager to use rainbow animation mode and improve LED control

Refactor LEDManager to use hardware-driven animations and simplify LED control methods

Remove test_sweep.py

Use sweep animation during audio playback too

Replace breathing-rgb with green-blue sweep animation

Replace software LED chase with hardware breathing-rgb animation

Use green LEDs for speech capture and add chase animation for waiting states

Fix EROFS: allow write access to ~/.openclaw in systemd service

Add NVM node path to systemd service PATH

Expand systemd service docs in README

Fix silence detection: use ambient-relative threshold

Fix silence detection never triggering