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/TunnelWarpShader.metal

@@ -0,0 +1,136 @@
+//
+//  TunnelWarpShader.metal
+//  PsytranceVisualizer
+//
+//  Infinite tunnel effect with warp distortion
+//
+
+#include <metal_stdlib>
+using namespace metal;
+
+#include "Common.metal"
+
+fragment float4 tunnelWarpFragment(
+    VertexOut in [[stage_in]],
+    constant ShaderUniforms& uniforms [[buffer(0)]],
+    constant float* fftData [[buffer(1)]],
+    constant float* melData [[buffer(2)]],
+    constant float* historyData [[buffer(3)]]
+) {
+    float2 uv = in.uv;
+    float2 resolution = uniforms.resolution;
+    float time = uniforms.time;
+    float reactivity = uniforms.reactivity;
+
+    float subBass = uniforms.subBassEnergy;
+    float pump = uniforms.sidechainPump;
+    float hnr = uniforms.hnrRatio;
+
+    // Center and aspect correction
+    float aspectRatio = resolution.x / resolution.y;
+    float2 p = (uv - 0.5) * 2.0;
+    p.x *= aspectRatio;
+
+    // Convert to polar coordinates for tunnel
+    float dist = length(p);
+    float angle = atan2(p.y, p.x);
+
+    // Avoid division by zero at center
+    dist = max(dist, 0.001);
+
+    // Tunnel depth (inverse of distance)
+    float depth = 1.0 / dist;
+
+    // Speed controlled by sub-bass
+    float baseSpeed = 2.0;
+    float audioSpeed = subBass * 3.0 * (0.5 + reactivity * 0.5);
+    float speed = baseSpeed + audioSpeed;
+
+    // Warp distortion from sidechain pump
+    float warpAmount = pump * 0.5;
+    depth += sin(angle * 4.0 + time * 2.0) * warpAmount * 0.5;
+    angle += sin(depth * 2.0 + time) * warpAmount * 0.3;
+
+    // Create tunnel coordinates
+    float2 tunnelUV = float2(
+        angle / (2.0 * 3.14159) + 0.5, // Angular coordinate [0, 1]
+        depth + time * speed            // Depth with movement
+    );
+
+    // === TUNNEL WALL PATTERNS ===
+
+    // Hexagonal grid pattern
+    float2 hexUV = tunnelUV * float2(8.0, 2.0);
+    float2 hexCell = floor(hexUV);
+    float2 hexFrac = fract(hexUV);
+
+    // Offset every other row
+    if (fmod(hexCell.y, 2.0) > 0.5) {
+        hexFrac.x = fract(hexFrac.x + 0.5);
+    }
+
+    float hexDist = length(hexFrac - 0.5);
+    float hexPattern = smoothstep(0.4, 0.35, hexDist);
+
+    // Add concentric rings
+    float rings = sin(tunnelUV.y * 20.0) * 0.5 + 0.5;
+    rings = smoothstep(0.3, 0.7, rings);
+
+    // Angular segments
+    float segments = 8.0;
+    float angularLines = abs(sin(angle * segments));
+    angularLines = smoothstep(0.95, 1.0, angularLines);
+
+    // Combine patterns
+    float pattern = hexPattern * 0.5 + rings * 0.3 + angularLines * 0.2;
+
+    // === COLORING ===
+
+    // Base color cycles with depth and time
+    float colorPhase = tunnelUV.y * 0.1 + time * 0.2;
+    float3 tunnelColor = psytrancePalette(colorPhase, time);
+
+    // Depth fog (darker towards center/infinity)
+    float fog = exp(-dist * 2.0);
+    tunnelColor *= fog;
+
+    // Pattern overlay
+    float3 patternColor = mix(uvViolet, neonCyan, rings);
+    tunnelColor = mix(tunnelColor, patternColor, pattern * 0.5);
+
+    // Edge glow (bright at tunnel edges)
+    float edgeGlow = exp(-dist * 5.0);
+    tunnelColor = addGlow(tunnelColor, (1.0 - edgeGlow) * 0.3, neonMagenta);
+
+    // Center light (looking into the tunnel)
+    float centerLight = exp(-dist * dist * 50.0);
+    tunnelColor += float3(1.0) * centerLight * 0.5;
+
+    // HNR affects pattern complexity
+    float patternIntensity = hnr;
+    tunnelColor *= 0.7 + patternIntensity * 0.3;
+
+    // Add noise for texture
+    float noiseVal = noise(tunnelUV * 10.0 + time);
+    tunnelColor += uvViolet * noiseVal * 0.1;
+
+    // Pump flash
+    if (pump > 0.5) {
+        float pumpFlash = (pump - 0.5) * 2.0;
+        tunnelColor += neonMagenta * pumpFlash * 0.2;
+    }
+
+    // Peak flash
+    if (uniforms.isPeak > 0.5) {
+        float peakFlash = uniforms.peakIntensity;
+        tunnelColor += float3(1.0) * peakFlash * 0.15 * (1.0 - edgeGlow);
+    }
+
+    // Speed lines effect
+    float speedLines = fract(tunnelUV.y * 50.0 - time * speed * 2.0);
+    speedLines = smoothstep(0.95, 1.0, speedLines);
+    speedLines *= subBass * 0.5;
+    tunnelColor += neonCyan * speedLines;
+
+    return float4(tunnelColor, 1.0);
+}