docs: update README development section to use uv

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: appleboy

README.md

@@ -92,7 +92,7 @@ def protected():
 ## Development
 
 ```bash
-pip install -e ".[dev]"
+make install    # uv sync --all-extras
 make test
 make lint
 make typecheck