Enables webcam, WebMIDI, and optional Audio Frequency Listener.
MIDI or Audio-Reactive Mode:
LOW / BASS → Random background + brightness hits.
MID RANGE → Glitch effect switching + pattern variations.
HIGH RANGE → Noise bursts, tear cuts, and chaos.
When MIDI is silent, the engine automatically listens to the audio frequency spectrum.
H hides / restores the HUD.