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>

README.md

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+# Paint UI
+
+A modern, browser-based image editor built with Next.js 16 and Tailwind CSS 4. Inspired by miniPaint, reimagined for the modern web.
+
+## Features (Planned)
+
+- 🎨 **Multi-layer Canvas** - Professional layer system with blend modes
+- 🖌️ **Drawing Tools** - Pencil, brush, eraser, fill, and selection tools
+- ✨ **Image Effects** - 50+ filters and effects (blur, sharpen, color adjustments)
+- 📝 **Text Tool** - Add text with web fonts
+- 🔄 **Undo/Redo** - Full history system
+- 💾 **File Support** - Open/save PNG, JPG, WEBP, GIF, and project files
+- 🎭 **Dark Mode** - Beautiful dark and light themes
+- ⌨️ **Keyboard Shortcuts** - Power user friendly
+- 📱 **Responsive** - Works on desktop, tablet, and mobile
+
+## Tech Stack
+
+- **Framework**: Next.js 16 (App Router)
+- **UI**: React 19 + TypeScript
+- **Styling**: Tailwind CSS 4
+- **Components**: Radix UI / Shadcn
+- **State**: Zustand
+- **Canvas**: HTML5 Canvas API + Web Workers
+
+## Getting Started
+
+### Prerequisites
+
+- Node.js 20+
+- pnpm 9+
+
+### Installation
+
+```bash
+# Clone repository
+git clone ssh://git@dev.pivoine.art:2222/valknar/paint-ui.git
+cd paint-ui
+
+# Install dependencies
+pnpm install
+
+# Run development server
+pnpm dev
+```
+
+Open [http://localhost:3000](http://localhost:3000) in your browser.
+
+## Documentation
+
+- [Implementation Plan](./IMPLEMENTATION_PLAN.md) - Detailed roadmap and architecture
+- [Contributing Guide](./docs/contributing.md) - How to contribute (coming soon)
+- [API Documentation](./docs/api.md) - Plugin API reference (coming soon)
+
+## Inspiration
+
+This project is inspired by [miniPaint](https://github.com/viliusle/miniPaint), an excellent open-source image editor. While paint-ui is a complete rewrite with modern technologies, we aim to preserve the powerful capabilities that make miniPaint great.
+
+## License
+
+MIT
+
+## Author
+
+valknar
+
+## Repository
+
+https://dev.pivoine.art/valknar/paint-ui