chore: initialize paint-ui project with comprehensive implementation plan

- Add detailed 18-week implementation roadmap
- Define architecture and tech stack (Next.js 16, Tailwind CSS 4)
- Plan 12 development phases from foundation to deployment
- Include directory structure and component organization
- Set performance targets and success metrics
- Document browser compatibility and API requirements

Inspired by miniPaint, reimagined for modern web development.

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

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

.gitignore

@@ -0,0 +1,49 @@
+# Dependencies
+node_modules/
+.pnp
+.pnp.js
+.yarn/
+
+# Testing
+coverage/
+.nyc_output/
+
+# Next.js
+.next/
+out/
+build/
+dist/
+
+# Production
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# Environment
+.env
+.env*.local
+.env.production
+
+# Vercel
+.vercel
+
+# TypeScript
+*.tsbuildinfo
+next-env.d.ts
+
+# OS
+.DS_Store
+Thumbs.db
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# Misc
+.cache/
+.turbo/