Add root Makefile for documentation build and serve workflows

Provides three convenient targets:
- build-docs: Build Sphinx documentation
- docs: Build and serve with simple HTTP server on port 8001
- preview: Build and serve with auto-reload on port 8001

All commands use uv run to ensure proper virtual environment activation.

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

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

Author: geyang

Makefile

@@ -0,0 +1,21 @@
+.PHONY: build-docs docs preview help
+
+help:
+	@echo "Available targets:"
+	@echo "  build-docs  - Build the Sphinx documentation"
+	@echo "  docs        - Build and serve documentation with auto-reload"
+	@echo "  preview     - Build and preview documentation in browser"
+
+build-docs:
+	@echo "Building documentation..."
+	uv run sphinx-build -M html docs docs/_build
+
+docs: build-docs
+	@echo "Starting documentation server at http://127.0.0.1:8001"
+	@echo "Press Ctrl+C to stop the server"
+	cd docs/_build/html && uv run python -m http.server 8001
+
+preview: build-docs
+	@echo "Starting documentation server with auto-reload..."
+	@echo "Documentation will be available at http://127.0.0.1:8001"
+	uv run sphinx-autobuild docs docs/_build/html --port 8001 --open-browser