Doobie v0.18.0

Visualisation
* Stereo waveform scope embedded in the tape loop (newest on the
  left, vertically centred in the empty interior between strands).
* Live oscilloscope on every LFO card — sine glides, square jumps,
  saw teeth, S&H teleports, all read distinctly.
* Inline per-slot source scope on every Matrix row (LFO 1..4 / Env).
* Live (source × amount) overlay on the Matrix amount slider — fill
  grows + for positive, − for negative, dot marks the live applied
  value.
* Mod-indicator dots on every knob now trace the actual live source
  value. Fixed regressions on the big DELAY Time / Feedback knobs
  and the per-head Pan / Time (1-vs-0-indexed lookup bug).

Modulation
* Each LFO grows an Offset knob (bipolar DC bias, -1..+1) so a
  symmetric sine can be biased into a unipolar swell or any partial
  shift in between.
* InputGain destination so the mod matrix can drive the input drive
  (±12 dB).

Pitch
* Granular shifter algorithm (Eventide-style, ~12 ms latency, clean
  ±24 st) selectable per-instance alongside the FFT phase vocoder.
* Pitch route: Feedback (classic compounding) or Pre (shift once on
  input).
* Latency compensation: both shifters report getLatencySamples(); the
  engine subtracts that from every tape-read distance so wet aligns
  to dry on every repeat regardless of feedback amount.

UX
* Preset name shows " *" when params have been edited since last
  load/save. Switching presets (browser row click OR header arrows)
  prompts Cancel / Discard / Save…. Dirty diff now uses a snapshot
  of the freshly-loaded values so settling and relay-init noise
  don't falsely mark the preset dirty.
* Mod drawer scrim less aggressive (0.55 → 0.25 opacity).
* User-saved presets continue to appear under the USER filter in
  the browser modal.
* Convolution mode: IR Speed knob restored.

Engine
* BBD clock noise now scales with the AGE knob — clean by default.
* 16 vocal-FX presets (Vox Slap, Doubler, Hall, Plate, Shimmer,
  Dub Vox Echo, Whisper Wash, Tape Vox, Telephone, Ghost Octave,
  Cathedral, Fifth Stack, Stereo Doubler, Megaphone, Frozen Pad,
  MIDI Harmonizer) — factory bank now 80.