feat(build): add backend-focused testing commands

- Add 'make full-check-backend' for fast backend testing without E2E
- Add 'make test-backend' for unit and integration tests only
- Update 'test:integration' to use Jest instead of bun for consistency
- Improve command descriptions for clarity
- Enable fast development workflow by skipping E2E tests when not needed

Makefile

@@ -76,6 +76,10 @@ test-e2e-report: ## Show e2e test report
 	@echo "$(BLUE)Showing e2e test report...$(RESET)"
 	@bun run test:e2e:report
 
+test-backend: ## Run backend tests (unit + integration)
+	@echo "$(BLUE)Running backend tests...$(RESET)"
+	@bun run test && bun run test:integration
+
 test-all: ## Run all tests (unit + integration + e2e)
 	@echo "$(BLUE)Running all tests...$(RESET)"
 	@bun run test:all
@@ -233,7 +237,10 @@ start: dev ## Alias for dev (start development server)
 build-and-test: build test ## Build and run tests
 	@echo "$(GREEN)Build and test completed!$(RESET)"
 
-full-check: lint test-all ## Run full code quality check
+full-check-backend: lint test-backend ## Run backend code quality check (unit + integration tests only)
+	@echo "$(GREEN)Backend check completed!$(RESET)"
+
+full-check: lint test-all ## Run full code quality check (includes unit + integration + E2E tests)
 	@echo "$(GREEN)Full check completed!$(RESET)"
 
 quick-deploy: build k8s-deploy ## Quick build and deploy to Kubernetes