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/EnvelopePanel.cpp

@@ -0,0 +1,63 @@
+#include "EnvelopePanel.h"
+
+EnvelopePanel::EnvelopePanel()
+{
+    titleLabel.setText ("ENVELOPE", juce::dontSendNotification);
+    titleLabel.setJustificationType (juce::Justification::centredLeft);
+    titleLabel.setColour (juce::Label::textColourId, InstaGrainLookAndFeel::textPrimary);
+    addAndMakeVisible (titleLabel);
+
+    setupKnob (attackKnob, aLabel, "A", 0.001, 2.0, 0.01, " s");
+    setupKnob (decayKnob, dLabel, "D", 0.001, 2.0, 0.1, " s");
+    setupKnob (sustainKnob, sLabel, "S", 0.0, 1.0, 1.0);
+    setupKnob (releaseKnob, rLabel, "R", 0.01, 5.0, 0.3, " s");
+
+    attackKnob.setSkewFactorFromMidPoint (0.2);
+    decayKnob.setSkewFactorFromMidPoint (0.3);
+    releaseKnob.setSkewFactorFromMidPoint (0.5);
+}
+
+void EnvelopePanel::setupKnob (juce::Slider& knob, juce::Label& label, const juce::String& name,
+                                double min, double max, double def, const juce::String& suffix)
+{
+    knob.setSliderStyle (juce::Slider::RotaryHorizontalVerticalDrag);
+    knob.setTextBoxStyle (juce::Slider::TextBoxBelow, false, 50, 14);
+    knob.setRange (min, max);
+    knob.setValue (def);
+    knob.setTextValueSuffix (suffix);
+    knob.getProperties().set (InstaGrainLookAndFeel::knobTypeProperty, "orange");
+    addAndMakeVisible (knob);
+
+    label.setText (name, juce::dontSendNotification);
+    label.setJustificationType (juce::Justification::centred);
+    label.setColour (juce::Label::textColourId, InstaGrainLookAndFeel::textSecondary);
+    addAndMakeVisible (label);
+}
+
+void EnvelopePanel::resized()
+{
+    auto bounds = getLocalBounds().reduced (4);
+    titleLabel.setBounds (bounds.removeFromTop (20));
+
+    int knobW = bounds.getWidth() / 4;
+
+    juce::Slider* knobs[] = { &attackKnob, &decayKnob, &sustainKnob, &releaseKnob };
+    juce::Label* labels[] = { &aLabel, &dLabel, &sLabel, &rLabel };
+
+    for (int i = 0; i < 4; ++i)
+    {
+        auto col = bounds.removeFromLeft (knobW);
+        auto knobArea = col.withTrimmedBottom (16);
+        knobs[i]->setBounds (knobArea.reduced (2));
+        labels[i]->setBounds (col.getX(), knobArea.getBottom() - 2, col.getWidth(), 16);
+    }
+}
+
+void EnvelopePanel::paint (juce::Graphics& g)
+{
+    auto bounds = getLocalBounds().toFloat();
+    g.setColour (InstaGrainLookAndFeel::bgMedium.withAlpha (0.5f));
+    g.fillRoundedRectangle (bounds, 4.0f);
+    g.setColour (InstaGrainLookAndFeel::bgLight.withAlpha (0.3f));
+    g.drawRoundedRectangle (bounds, 4.0f, 1.0f);
+}