Initial release — InstaGrain granular synthesizer v1.0

8-voice polyphonic granular synth (VST3/AU/LV2) with:
- 128 grain pool per voice, Hann windowing, linear interpolation
- Root note selector, sample rate correction, sustain pedal (CC64)
- Scatter controls, direction modes (Fwd/Rev/PingPong), freeze
- ADSR envelope, global filter (LP/HP/BP), reverb
- Waveform display with grain visualization
- Drag & drop sample loading, full state save/restore
- CI/CD for Windows/macOS/Linux

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Source/WaveformDisplay.h

@@ -0,0 +1,38 @@
+#pragma once
+#include <JuceHeader.h>
+#include "GrainEngine.h"
+
+class WaveformDisplay : public juce::Component
+{
+public:
+    WaveformDisplay();
+
+    void setBuffer (const juce::AudioBuffer<float>* buffer);
+    void setGrainPosition (float pos) { grainPosition = pos; repaint(); }
+    void setScatterRange (float range) { scatterRange = range; repaint(); }
+    void setActiveGrains (const std::vector<GrainEngine::ActiveGrainInfo>& grains);
+
+    std::function<void (float)> onPositionChanged;
+
+    void paint (juce::Graphics& g) override;
+    void resized() override;
+    void mouseDown (const juce::MouseEvent& e) override;
+    void mouseDrag (const juce::MouseEvent& e) override;
+
+private:
+    const juce::AudioBuffer<float>* audioBuffer = nullptr;
+    juce::Path cachedWaveformPath;
+    bool pathDirty = true;
+    int lastWidth = 0, lastHeight = 0;
+    int lastBufferSize = 0;
+
+    float grainPosition = 0.5f;
+    float scatterRange = 0.0f;
+    std::vector<GrainEngine::ActiveGrainInfo> activeGrains;
+    int totalSourceSamples = 0;
+
+    void rebuildWaveformPath (juce::Rectangle<float> bounds);
+    void updatePositionFromMouse (const juce::MouseEvent& e);
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (WaveformDisplay)
+};