build: add Makefile for dev, test, and build orchestration

Makefile

@@ -0,0 +1,57 @@
+BINARY  := nib
+MODULE  := github.com/lerko/nib
+GOFLAGS := -trimpath
+
+.PHONY: build dev test lint fmt vet clean run help
+
+## —— Build ——————————————————————————————————
+
+build: ## Build production binary
+	go build $(GOFLAGS) -o $(BINARY) .
+
+dev: ## Build and run with default serve
+	go run . serve
+
+## —— Quality ————————————————————————————————
+
+test: ## Run all tests
+	go test ./...
+
+test-v: ## Run all tests (verbose)
+	go test -v ./...
+
+test-cover: ## Run tests with coverage report
+	go test -coverprofile=coverage.out ./...
+	go tool cover -func=coverage.out
+	@rm -f coverage.out
+
+lint: vet fmt-check ## Run all linters
+
+vet: ## Run go vet
+	go vet ./...
+
+fmt: ## Format all Go files
+	gofmt -w .
+
+fmt-check: ## Check formatting (fails if unformatted)
+	@test -z "$$(gofmt -l .)" || (echo "unformatted files:" && gofmt -l . && exit 1)
+
+## —— Utility ————————————————————————————————
+
+clean: ## Remove build artifacts
+	rm -f $(BINARY) coverage.out
+
+run: build ## Build then run with args (usage: make run ARGS="serve")
+	./$(BINARY) $(ARGS)
+
+tidy: ## Tidy and verify module dependencies
+	go mod tidy
+	go mod verify
+
+## —— Help ———————————————————————————————————
+
+help: ## Show this help
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | \
+		awk 'BEGIN {FS = ":.*?## "}; {printf "  \033[36m%-14s\033[0m %s\n", $$1, $$2}'
+
+.DEFAULT_GOAL := help