Initial release — InstaShadow mastering compressor v1.0

Dual-stage compressor (optical + VCA) with output transformer saturation.
- Port-Hamiltonian T4B opto-cell model with implicit trapezoidal integration
- Feed-forward VCA with 7 ratios, 6 attack/release presets, Dual release mode
- 3 transformer types (Nickel/Iron/Steel) with 4x oversampled waveshaping
- Analog-style needle VU meters, horizontal GR meters
- Sidechain HPF, stereo link, independent section bypass
- Full state save/restore, CI/CD for Windows/macOS/Linux

Source/VuMeter.h

@@ -0,0 +1,62 @@
+#pragma once
+#include <JuceHeader.h>
+
+class VuMeter : public juce::Component
+{
+public:
+    void setLevel (float left, float right)
+    {
+        if (left > peakL) peakL = left;
+        else peakL *= 0.995f;
+        if (right > peakR) peakR = right;
+        else peakR *= 0.995f;
+
+        levelL = std::max (left, levelL * 0.85f);
+        levelR = std::max (right, levelR * 0.85f);
+        repaint();
+    }
+
+    void paint (juce::Graphics& g) override
+    {
+        auto bounds = getLocalBounds().toFloat().reduced (1);
+        float barGap = 2.0f;
+        float halfW = (bounds.getWidth() - barGap) / 2.0f;
+        auto leftBar  = bounds.removeFromLeft (halfW);
+        bounds.removeFromLeft (barGap);
+        auto rightBar = bounds;
+
+        drawBar (g, leftBar, levelL, peakL);
+        drawBar (g, rightBar, levelR, peakR);
+    }
+
+private:
+    float levelL = 0.0f, levelR = 0.0f;
+    float peakL = 0.0f, peakR = 0.0f;
+
+    void drawBar (juce::Graphics& g, juce::Rectangle<float> bar, float level, float peak)
+    {
+        g.setColour (juce::Colour (0xff111122));
+        g.fillRoundedRectangle (bar, 2.0f);
+
+        float displayLevel = std::pow (juce::jlimit (0.0f, 1.0f, level), 0.5f);
+        float h = bar.getHeight() * displayLevel;
+        auto filled = bar.withTop (bar.getBottom() - h);
+
+        if (displayLevel < 0.6f)
+            g.setColour (juce::Colour (0xff00cc44));
+        else if (displayLevel < 0.85f)
+            g.setColour (juce::Colour (0xffcccc00));
+        else
+            g.setColour (juce::Colour (0xffff3333));
+
+        g.fillRoundedRectangle (filled, 2.0f);
+
+        float displayPeak = std::pow (juce::jlimit (0.0f, 1.0f, peak), 0.5f);
+        if (displayPeak > 0.01f)
+        {
+            float peakY = bar.getBottom() - bar.getHeight() * displayPeak;
+            g.setColour (juce::Colours::white.withAlpha (0.8f));
+            g.fillRect (bar.getX(), peakY, bar.getWidth(), 1.5f);
+        }
+    }
+};