feat: initialize Next.js 16 project with Tailwind CSS 4 and Docker support

Phase 1 Implementation:
- Set up Next.js 16 with React 19, TypeScript 5, and Turbopack
- Configure Tailwind CSS 4 with OKLCH color system
- Implement dark/light theme support
- Create core UI components: Button, Card, Slider, Progress, Toast
- Add ThemeToggle component for theme switching
- Set up project directory structure for audio editor
- Create storage utilities for settings management
- Add Dockerfile with multi-stage build (Node + nginx)
- Configure nginx for static file serving with caching
- Add docker-compose.yml for easy deployment
- Configure static export mode for production

Tech Stack:
- Next.js 16 with Turbopack
- React 19
- TypeScript 5
- Tailwind CSS 4
- pnpm 9.0.0
- nginx 1.27 (for Docker deployment)

Build verified and working ✓

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

next.config.ts

@@ -0,0 +1,28 @@
+import type { NextConfig } from 'next';
+
+const nextConfig: NextConfig = {
+  output: 'export',
+  reactStrictMode: true,
+  // Turbopack configuration (Next.js 16+)
+  turbopack: {},
+  // Webpack fallback for older Next.js versions
+  webpack: (config) => {
+    // Required for Web Audio API and WASM modules
+    config.resolve.fallback = {
+      ...config.resolve.fallback,
+      fs: false,
+      path: false,
+      crypto: false,
+    };
+
+    // Enable WASM
+    config.experiments = {
+      ...config.experiments,
+      asyncWebAssembly: true,
+    };
+
+    return config;
+  },
+};
+
+export default nextConfig;