build: introduce Makefile for unified build, lint, and dev workflows

- Add Makefile to automate building, testing, linting, and development workflows
- Include targets for building on multiple platforms, hot reload support, and code generation with templ
- Add linting, formatting, and dependency management tasks
- Provide Docker integration for build and run
- Implement tool checks and project cleanup commands

Signed-off-by: appleboy <appleboy.tw@gmail.com>

Author: appleboy

Makefile

@@ -0,0 +1,131 @@
+GO ?= go
+EXECUTABLE := cli
+GOFILES := $(shell find . -type f -name "*.go")
+TAGS ?=
+TEMPL_VERSION ?= latest
+
+ifneq ($(shell uname), Darwin)
+	EXTLDFLAGS = -extldflags "-static" $(null)
+else
+	EXTLDFLAGS =
+endif
+
+ifneq ($(DRONE_TAG),)
+	VERSION ?= $(DRONE_TAG)
+else
+	VERSION ?= $(shell git describe --tags --always || git rev-parse --short HEAD)
+endif
+COMMIT ?= $(shell git rev-parse --short HEAD)
+
+LDFLAGS ?=
+## build: build the authgate binary
+build: generate $(EXECUTABLE)
+
+$(EXECUTABLE): $(GOFILES)
+	$(GO) build -v -tags '$(TAGS)' -ldflags '$(EXTLDFLAGS)-s -w $(LDFLAGS)' -o bin/$@ .
+
+## air: Install air for hot reload.
+air:
+	@hash air > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		$(GO) install github.com/air-verse/air@latest; \
+	fi
+
+## dev: Run the application with hot reload.
+dev: air
+	air
+
+## install: install the authgate binary
+install: $(GOFILES)
+	$(GO) install -v -tags '$(TAGS)' -ldflags '$(EXTLDFLAGS)-s -w $(LDFLAGS)'
+
+## test: run tests
+test: generate
+	@$(GO) test -v -cover -coverprofile coverage.txt ./... && echo "\n==>\033[32m Ok\033[m\n" || exit 1
+
+## coverage: view test coverage in browser
+coverage: test
+	$(GO) tool cover -html=coverage.txt
+
+## install-golangci-lint: install golangci-lint if not present
+install-golangci-lint:
+	@command -v golangci-lint >/dev/null 2>&1 || curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/HEAD/install.sh | sh -s -- -b $$($(GO) env GOPATH)/bin v2.7.2
+
+## fmt: format go files using golangci-lint
+fmt: install-golangci-lint
+	golangci-lint fmt
+
+## lint: run golangci-lint to check for issues
+lint: install-golangci-lint
+	golangci-lint run
+
+## build_linux_amd64: build the authgate binary for linux amd64
+build_linux_amd64: generate
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 $(GO) build -a -tags '$(TAGS)' -ldflags '$(EXTLDFLAGS)-s -w $(LDFLAGS)' -o release/linux/amd64/$(EXECUTABLE) .
+
+## build_linux_arm64: build the authgate binary for linux arm64
+build_linux_arm64: generate
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 $(GO) build -a -tags '$(TAGS)' -ldflags '$(EXTLDFLAGS)-s -w $(LDFLAGS)' -o release/linux/arm64/$(EXECUTABLE) .
+
+## clean: remove build artifacts and test coverage
+clean:
+	rm -rf bin/ release/ coverage.txt
+	find internal/templates -name "*_templ.go" -delete
+
+## rebuild: clean and build
+rebuild: clean build
+
+.PHONY: help build install test coverage fmt lint clean rebuild
+.PHONY: build_linux_amd64 build_linux_arm64
+.PHONY: install-templ generate watch air dev
+.PHONY: install-golangci-lint mod-download mod-tidy mod-verify check-tools version
+.PHONY: docker-build docker-run
+
+## install-templ: install templ CLI if not installed
+install-templ:
+	@command -v templ >/dev/null 2>&1 || $(GO) install github.com/a-h/templ/cmd/templ@$(TEMPL_VERSION)
+
+## generate: run templ generate to compile .templ files
+generate: install-templ
+	templ generate
+
+## watch: watch mode for automatic regeneration
+watch: install-templ
+	templ generate --watch
+
+## help: print this help message
+help:
+	@echo 'Usage:'
+	@sed -n 's/^##//p' ${MAKEFILE_LIST} | column -t -s ':' | sed -e 's/^/ /'
+
+## mod-download: download go module dependencies
+mod-download:
+	$(GO) mod download
+
+## mod-tidy: tidy go module dependencies
+mod-tidy:
+	$(GO) mod tidy
+
+## mod-verify: verify go module dependencies
+mod-verify:
+	$(GO) mod verify
+
+## check-tools: verify required tools are installed
+check-tools:
+	@command -v $(GO) >/dev/null 2>&1 || (echo "Go not found" && exit 1)
+	@command -v templ >/dev/null 2>&1 || echo "templ not installed (run: make install-templ)"
+	@command -v golangci-lint >/dev/null 2>&1 || echo "golangci-lint not installed (run: make install-golangci-lint)"
+
+## version: display version information
+version:
+	@echo "Version: $(VERSION)"
+	@echo "Commit: $(COMMIT)"
+	@echo "Go Version: $(shell $(GO) version)"
+
+## docker-build: build docker image
+docker-build:
+	docker build -t authgate:$(VERSION) -f Dockerfile .
+
+## docker-run: run docker container
+docker-run:
+	docker run -p 8080:8080 --env-file .env authgate:$(VERSION)
+