feat: add Draw (Excalidraw) tool as 6th tool

- Added Draw tool to ToolsGrid with collaborative badges
- Updated Stats component to show 6 tools
- Updated Footer to show 6 tools and include Draw link
- Updated README with Draw tool description
- Draw tool accessible at draw.kit.pivoine.art

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

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

README.md

@@ -136,6 +136,7 @@ Tailwind CSS 4 uses a new CSS-first configuration approach:
 - **Pastel** - Modern color manipulation toolkit with palette generation and accessibility testing
 - **Stirling** - Powerful PDF toolkit with 50+ operations (merge, split, convert, OCR, sign)
 - **Units** - Smart unit converter with 187 units across 23 categories (length, mass, temperature, etc.)
+- **Draw** - Virtual whiteboard for sketching hand-drawn style diagrams (flowcharts, wireframes, collaborative editing)
 
 ## CI/CD Pipeline