feat: add conditional help target in Makefile (#36)

Add RULES_SKIP_HELP environment variable check to conditionally skip help target.
This allows external tools to suppress help output when needed.

Author: shunkakinoki

Makefile

@@ -62,8 +62,10 @@ mcp-sync: ## Sync MCP configuration from .ruler/mcp.json to CLI tools.
 # HELP
 # ====================================================================================
 
+ifeq ($(RULES_SKIP_HELP),)
 .PHONY: help
 help: ## Show this help message.
 	@echo "Usage: make <target>"
 	@echo
 	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z0-9_-]+:.*?## / {printf "  \033[36m%-20s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)
+endif