feat: Connect effects engine to live audio playback path

[ChuxiJ]

Problem

EffectsEngine.ts exists with 10+ effect types (EQ3, Compressor, Reverb, Delay, Distortion, Chorus, Flanger, Phaser, Filter, Sidechain), but effects are not connected to the live audio signal chain. Users can add effects to tracks and tweak parameters, but hear completely dry audio during playback.

This is the single most impactful gap in the current DAW — it makes the entire effects system decorative.

Proposed Solution

1. Refactor EffectsEngine to use native Web Audio nodes (or Tone.js equivalents that integrate cleanly)
2. Insert effect chain between TrackNode source and master bus in AudioEngine
3. Ensure parameter changes reflect in real-time (< 16ms)
4. Support bypass per-effect and per-chain
5. Handle effect chain reordering without audio glitches

Technical Notes

• Reference: TASK_QUEUE.md item S1-03
• Key files: src/engine/EffectsEngine.ts, src/engine/AudioEngine.ts, src/engine/TrackNode.ts
• Blocked by: nothing
• Blocks: WAV export with effects (separate issue)

Acceptance Criteria

• Adding an effect to a track audibly changes playback output
• Removing an effect reverts to dry signal
• Effect parameter changes are audible in real-time
• Bypass toggle works per-effect
• Reordering effects chain changes the sound
• No audio glitches when adding/removing effects during playback
• Unit tests for effect chain signal routing
• E2E test: add reverb → verify wet signal (or at least verify no errors)

[ChuxiJ]

Closing as already implemented. useEffectsSync hook in AppShell.tsx (line 107) connects effects to live audio via effectsEngine.rebuildChain() → trackNode.spliceEffects(). All 10 effect types are created as Tone.js nodes and spliced between eqHigh and dry/wet split in the TrackNode signal chain.

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