fix: mark docs target as .PHONY in Makefile

Makefile

@@ -1,4 +1,4 @@
-.PHONY: help fees match web image run sync sync-2026 test test-v
+.PHONY: help fees match web image run sync sync-2026 test test-v docs
 
 export PYTHONPATH := scripts:$(PYTHONPATH)
 VENV := .venv
@@ -25,6 +25,7 @@ help:
 	@echo "  make venv        - Sync virtual environment with pyproject.toml"
 	@echo "  make test        - Run web application infrastructure tests"
 	@echo "  make test-v      - Run tests with verbose output"
+	@echo "  make docs        - Serve documentation in a browser"
 
 venv:
 	uv sync
@@ -61,3 +62,8 @@ test: $(PYTHON) ## Run web application tests
 
 test-v: $(PYTHON) ## Run tests with verbose output
 	export PYTHONPATH=$(PYTHONPATH):$(CURDIR)/scripts:$(CURDIR) && $(PYTHON) -m unittest discover -v tests
+
+docs: ## Serve documentation locally
+	@echo "Starting documentation server at http://localhost:8000"
+	@echo "Press Ctrl+C to stop."
+	$(PYTHON) -m http.server 8000 --directory docs