Doobie v0.18.1

Patch on top of v0.18.0:

* IR Speed slider drag no longer crackles. Was re-resampling the
  cached IR on every value tick during drag (30-60× per second)
  and tearing the convolver state. Now debounced — the heavy
  reload waits 120 ms past the last knob movement; the displayed
  value still tracks the param in real time.
* Dirty tracking refined: tolerance widened (1e-4 → 5e-3) so JS
  relay round-trip noise + APVTS XML sync ULP slip don't falsely
  flag the preset; snapshot deferred 80 ms past applyPreset so
  late-settling state lands before we anchor the clean reference.
  The asterisk no longer lights up without you touching anything.