- Add beep.c/beep.h: CPU-generated two-tone achievement chime
  via sceAudio (no audio files required)
- Fix rc_glue_update: collect ALL achievements that fire in one
  frame before updating delta snapshots, preventing simultaneous
  achievements from being skipped
- Fix draw thread: reduce idle sleep from 100ms to 16ms to
  prevent missing the first popup in a sequence
- Fix warmup: re-activate any achievement that fires during
  warmup phase so it triggers properly after warmup completes
- Update RC_EvalResult to return a batch of up to 8 unlocks
  per frame instead of a single result
- Raise beep amplitude to 18000 and volume to 50% for audibility