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

Set up complete Next.js 16 development environment:
- Next.js 16.0.1 with App Router and Turbopack
- React 19.2.0 with TypeScript 5.9
- Tailwind CSS 4.1.17 with custom category colors
- ESLint 9 with Next.js config
- Static site generation enabled (output: 'export')

Project structure:
- app/ directory with layout, page, and globals.css
- Tailwind config with 23 category-specific colors
- TypeScript config with strict mode and path aliases
- Complete .gitignore for Next.js projects

Dependencies installed:
- convert-units 2.3.4 for unit conversions
- All React 19 and Next.js 16 dependencies
- Development tooling (TypeScript, ESLint, Tailwind)

Ready for Phase 2: Core conversion engine implementation

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

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

tsconfig.json

@@ -0,0 +1,27 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["DOM", "DOM.Iterable", "ES2020"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "noEmit": true,
+    "esModuleInterop": true,
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "preserve",
+    "incremental": true,
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ],
+    "paths": {
+      "@/*": ["./*"]
+    }
+  },
+  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
+  "exclude": ["node_modules"]
+}