Performance:
- All every N statements with same interval now merge into one setInterval
- Pong: 24 timers → 1, Breakout: 38 timers → 1 (single DS.flush per frame)
New examples:
- game-breakout.ds: brick-breaker with 5×10 colored bricks, keyboard, audio
- beats-viewer.ds: step sequencer spectator via relay
Fixes:
- _playTone/_playNoise early-exit when freq/duration <= 0
- Breakout score race: score+bounce checks before brick destruction
- Score sound effects in pong (220Hz/440Hz sawtooth)
All 48 examples compile, 136 tests pass
