feat: implement granular pitch shifter

.gitignore

@@ -42,3 +42,10 @@ emscripten/temp_build/
 
 # Embedded git repository (should not be tracked as submodule)
 gpt_mini_work/contabo_storage_manager/
+public/*.js
+public/*.wasm
+src/wasm/*.js
+src/wasm/*.wasm
+src/wasm/*.d.ts
+public/audio-worklets/
+public/utils/

agent_plan.md

@@ -216,3 +216,5 @@
 * [2026-05-08] - Implemented AI Auto-EQ Assistant: Added a `bassSidechainEQBus` (peaking filter at 250Hz) to `initializeMasterOutput`. Implemented `triggerBassEQDuck` to dynamically duck this EQ band on the master synth bus whenever a Bass note (303 or synth bass) triggers, preventing low-mid frequency masking and fulfilling the AI Auto-EQ Assistant Innovation Lab idea. Added new ideas: "Vocal Overdrive Worklet" and "Rhythmic Gating".
 * [2026-05-12] - Implemented Performance Fixes for CI and TS Types: Cleaned up mismatched properties between `SamplerBankParams` UI and internal type definitions (`coarseTune`, `fineTune`, `formantShift`, `quality`, `lockToSequencer`). Cleaned up custom sequencer optimization patch.
 * [2026-08-01] - Implemented Time-Stretch Envelope: Added `timeStretchEnvDepth` to `Note` and `SamplerBankParams` interfaces. Wired the parameter through `NoteSelector` and `SamplerPanel` UI down to `useAudioEngine.ts` and `SingingVoice.ts`, and finally applied the dynamic time stretch modulation via the `envelopeValue` inside `rubberband-processor.ts`. Fulfills the "Time-Stretch Envelope" Innovation Lab idea. Added new idea: "Granular Pitch Shifter".
+* [2026-08-02] - Implemented Granular Pitch Shifter: Added `grainPitchShift` to `Note` and `SamplerBankParams` interfaces. Modulated `pitchScale` inside `rubberband-processor.ts` independently of basic tracking. Exposed to global `SamplerPanel` and per-step `NoteSelector` UI. Added new idea: "Formant Preserving Vocoder".
+* **Idea:** "Formant Preserving Vocoder" - Implement an FFT-based vocoder where synth A acts as carrier and the TTS sampler acts as modulator, preserving formants independently.