Add Psytrance Visualizer macOS app with Metal rendering

A complete audio-reactive visualizer for psytrance music featuring:

Audio Analysis (DSPEngine):
- FFT spectrum analysis via Accelerate/vDSP
- 64-band Mel spectrogram
- Sub-bass energy extraction (<100Hz)
- Automatic sidechain pump detection
- Harmonic-to-Noise ratio (HNR) calculation
- Peak/transient detection

8 Visualization Modes (Metal Shaders):
1. FFT Classic - Frequency spectrum bars with glow
2. Mel Spectrogram - Waterfall display
3. Sub-Bass - Pulsating rings
4. Sidechain Pump - Breathing zoom effect
5. Harmonic/Noise - Geometric vs chaotic particles
6. Mandelbrot - Audio-reactive fractal zoom
7. Tunnel Warp - Infinite tunnel with distortion
8. DMT Geometry - Sacred geometry patterns

Features:
- Selectable audio input device (BlackHole support)
- Configurable buffer size (512/1024)
- Reactivity slider for visual intensity
- Auto-hiding control panel
- Fullscreen support with keyboard shortcuts (1-8, F, ESC)
- Persistent settings via UserDefaults
- Psytrance-inspired neon/UV color palette

PsytranceVisualizer/Rendering/Shaders/FFTClassicShader.metal

@@ -0,0 +1,117 @@
+//
+//  FFTClassicShader.metal
+//  PsytranceVisualizer
+//
+//  Classic FFT bar visualization with glow effects
+//
+
+#include <metal_stdlib>
+using namespace metal;
+
+// Include common definitions
+#include "Common.metal"
+
+fragment float4 fftClassicFragment(
+    VertexOut in [[stage_in]],
+    constant ShaderUniforms& uniforms [[buffer(0)]],
+    constant float* fftData [[buffer(1)]]
+) {
+    float2 uv = in.uv;
+    float2 resolution = uniforms.resolution;
+    float time = uniforms.time;
+    float reactivity = uniforms.reactivity;
+
+    // Number of bars to display
+    const int numBars = 64;
+    const float barWidth = 1.0 / float(numBars);
+    const float barGap = barWidth * 0.2;
+    const float actualBarWidth = barWidth - barGap;
+
+    // Determine which bar this pixel belongs to
+    int barIndex = int(uv.x * float(numBars));
+    barIndex = clamp(barIndex, 0, numBars - 1);
+
+    // Get FFT magnitude for this bar (with some averaging for smoothness)
+    float magnitude = fftData[barIndex];
+
+    // Apply reactivity scaling
+    magnitude = magnitude * (0.5 + reactivity * 1.5);
+    magnitude = clamp(magnitude, 0.0, 1.0);
+
+    // Calculate bar position within its cell
+    float barCellX = fract(uv.x * float(numBars));
+    float barCenterX = 0.5;
+
+    // Distance from bar center (for width calculation)
+    float distFromCenter = abs(barCellX - barCenterX);
+    float halfWidth = actualBarWidth * 0.5 / barWidth;
+
+    // Check if we're inside the bar horizontally
+    bool insideBarX = distFromCenter < halfWidth;
+
+    // Bar height from bottom
+    float barHeight = magnitude;
+
+    // Add some bounce on peaks
+    if (uniforms.isPeak > 0.5) {
+        barHeight += uniforms.peakIntensity * 0.1 * sin(time * 20.0 + float(barIndex) * 0.3);
+    }
+
+    // Check if we're inside the bar vertically (from bottom)
+    float yFromBottom = 1.0 - uv.y;
+    bool insideBarY = yFromBottom < barHeight;
+
+    // Color based on frequency and magnitude
+    float colorPhase = float(barIndex) / float(numBars) + time * 0.05;
+    float3 barColor = psytrancePalette(colorPhase, time);
+
+    // Intensity gradient from bottom to top
+    float intensityGradient = yFromBottom / max(barHeight, 0.01);
+    intensityGradient = clamp(intensityGradient, 0.0, 1.0);
+
+    // Make top of bars brighter
+    barColor = mix(barColor * 0.6, barColor * 1.5, intensityGradient);
+
+    // Calculate glow
+    float glowRadius = 0.05 * (1.0 + magnitude);
+    float distToBar = 0.0;
+
+    if (!insideBarX) {
+        distToBar = (distFromCenter - halfWidth) * barWidth;
+    }
+    if (!insideBarY && yFromBottom >= barHeight) {
+        float vertDist = yFromBottom - barHeight;
+        distToBar = max(distToBar, vertDist);
+    }
+
+    float glow = exp(-distToBar * distToBar / (glowRadius * glowRadius * 2.0));
+    glow *= magnitude;
+
+    // Final color
+    float3 finalColor = float3(0.0);
+
+    if (insideBarX && insideBarY) {
+        // Inside the bar
+        finalColor = barColor;
+
+        // Add peak cap (bright line at top)
+        float capThickness = 0.01;
+        if (abs(yFromBottom - barHeight) < capThickness) {
+            finalColor = float3(1.0); // White cap
+        }
+    } else {
+        // Add glow outside bars
+        finalColor = barColor * glow * 0.5;
+    }
+
+    // Add subtle background pulse with sub-bass
+    float bgPulse = uniforms.subBassEnergy * 0.05;
+    finalColor += deepPurple * bgPulse;
+
+    // Add overall glow at peaks
+    if (uniforms.isPeak > 0.5) {
+        finalColor += neonMagenta * uniforms.peakIntensity * 0.1;
+    }
+
+    return float4(finalColor, 1.0);
+}