chore: add Makefile

Build targets:
- build: compile with version from git
- test: run full test suite
- install: install to GOPATH
- clean: remove binary
- gh-install: install as gh CLI extension

Author: boneskull

Makefile

@@ -0,0 +1,21 @@
+.PHONY: build test install clean
+
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
+LDFLAGS := -ldflags "-X github.com/boneskull/gh-stack/cmd.version=$(VERSION)"
+
+build:
+	go build $(LDFLAGS) -o gh-stack .
+
+test:
+	go test ./... -v
+
+install:
+	go install $(LDFLAGS) .
+
+clean:
+	rm -f gh-stack
+
+# Install as gh extension
+gh-install: build
+	mkdir -p ~/.local/share/gh/extensions/gh-stack
+	cp gh-stack ~/.local/share/gh/extensions/gh-stack/