Reduce processorCode size via feature-based conditional code generation

[Copilot]

The generated processorCode for AudioWorkletProcessors included all runtime helpers (~60 kB) regardless of which features a DSP actually used. Most DSPs don't use MIDI, sensors, or soundfiles, making this dead code.

Changes

Core types

• Added FaustFeatureFlags interface tracking hasMidi, hasAcc, hasGyr, hasSoundfiles, hasPoly
• Extended FaustData to include features: FaustFeatureFlags

Feature detection

• Added FaustBaseWebAudioDsp.detectFeatures() - walks DSP UI metadata to identify required features
• Added FaustBaseWebAudioDsp.mergeFeatureFlags() - combines flags for poly+effect DSPs

Conditional code generation

• Modified FaustDspGenerator to serialize only required runtime classes:
  • Core classes (FaustDspInstance, FaustBaseWebAudioDsp, FaustWasmInstantiator) always included
  • Soundfile/WasmAllocator only when hasSoundfiles
  • Sensor stack (FaustSensors, communicators) only when hasAcc or hasGyr
• Updated dependency injection to match serialized classes

Runtime optimization

• Modified FaustAudioWorkletProcessor to conditionally initialize sensor communicator
• Gated sensor polling with feature checks

Result

Basic DSPs drop from ~60 kB to ~10 kB processorCode. DSPs using optional features include only what they need.

// Before: always serializes all 10 classes
// After: selective serialization based on detected features
const featureFlags = FaustBaseWebAudioDsp.detectFeatures(meta);
const runtimeCtors = [/* core classes */];
if (featureFlags.hasSoundfiles) {
    runtimeCtors.push(/* soundfile classes */);
}

Original prompt

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