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/Package.swift

@@ -0,0 +1,41 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "PsytranceVisualizer",
+    platforms: [
+        .macOS(.v13)
+    ],
+    products: [
+        .executable(
+            name: "PsytranceVisualizer",
+            targets: ["PsytranceVisualizer"]
+        )
+    ],
+    targets: [
+        .executableTarget(
+            name: "PsytranceVisualizer",
+            path: ".",
+            exclude: [
+                "Package.swift",
+                "README.md"
+            ],
+            sources: [
+                "App",
+                "Audio",
+                "Models",
+                "Rendering",
+                "UI",
+                "Utilities"
+            ],
+            resources: [
+                .process("Resources")
+            ],
+            swiftSettings: [
+                .unsafeFlags(["-enable-bare-slash-regex"])
+            ]
+        )
+    ]
+)