feat: Add user role entity and integrate with user model, including migration updates and a new Makefile target.

Makefile

@@ -9,6 +9,7 @@ help:
 	@echo "  make dev       - Start development servers"
 	@echo "  make build     - Build for development"
 	@echo "  make release   - Build optimized production bundle"
+	@echo "  make migrate   - Run database migrations"
 	@echo "  make lint      - Run linters (Clippy + ESLint)"
 	@echo "  make typecheck - Type checking (Rust + TypeScript)"
 	@echo "  make test      - Run all tests"
@@ -16,10 +17,13 @@ help:
 	@echo "  make clean     - Clean build artifacts"
 
 # Backend commands
-.PHONY: backend-dev backend-build backend-release backend-lint backend-test
+.PHONY: backend-dev backend-build backend-release backend-lint backend-test migrate
+
+migrate:
+	cd backend && ./target/debug/zhealth migrate
 
 backend-dev:
-	cd backend && cargo run
+	cd backend && ./target/debug/zhealth serve
 
 backend-build:
 	cd backend && cargo build