build: add Makefile with release, snapshot, completions targets

Makefile

@@ -0,0 +1,39 @@
+.PHONY: build snapshot release completions clean help
+
+GO ?= go
+BIN := archduino
+
+help: ## Show this help
+	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {printf "  %-14s %s\n", $$1, $$2}' $(MAKEFILE_LIST)
+
+build: ## Local dev build into ./archduino
+	$(GO) build -o $(BIN) ./cmd/archduino
+
+completions: ## Regenerate shell completions into completions/
+	@mkdir -p completions
+	$(GO) run ./cmd/archduino completion bash > completions/archduino.bash
+	$(GO) run ./cmd/archduino completion zsh  > completions/_archduino
+	$(GO) run ./cmd/archduino completion fish > completions/archduino.fish
+
+snapshot: ## Local goreleaser dry run into dist/
+	goreleaser release --snapshot --clean
+
+clean: ## Remove build artifacts
+	rm -rf dist/ completions/ $(BIN)
+
+release: ## Compute next SemVer from commits, tag, and push
+	@command -v svu >/dev/null || { echo "svu not found. Run: go install github.com/caarlos0/svu@latest"; exit 1; }
+	@test -z "$$(git status --porcelain)" || { echo "working tree is dirty; commit or stash first"; exit 1; }
+	@branch=$$(git rev-parse --abbrev-ref HEAD); \
+	 if [ "$$branch" != "master" ]; then echo "must be on master (currently on $$branch)"; exit 1; fi
+	@current=$$(svu current 2>/dev/null || echo "none"); \
+	 next=$$(svu next); \
+	 echo "Current: $$current"; \
+	 echo "Next:    $$next"; \
+	 echo; \
+	 echo "Commits since $$current:"; \
+	 if [ "$$current" = "none" ]; then git log --oneline; else git log --oneline $$current..HEAD; fi; \
+	 echo; \
+	 printf "Tag %s and push? [y/N] " "$$next"; read ans; \
+	 if [ "$$ans" != "y" ] && [ "$$ans" != "Y" ]; then echo "aborted"; exit 1; fi; \
+	 git tag "$$next" && git push origin "$$next"