waitfordb: initial tool — env-configured wait-for-DB init container

Small Go tool + distroless container used as a K8s initContainer to block an
app until its database (Postgres/MySQL) is reachable. Env-var configured
(WAITFORDB_* + libpq PG* fallback), configurable timeout/interval, redacted
logs, exit codes. Woodpecker CI publishes docker-internal/waitfordb on tag.

Makefile

@@ -0,0 +1,58 @@
+BINARY  := waitfordb
+DIST    := dist
+IMAGE   := artifactapi.k8s.syd1.au.unkin.net/docker-internal/waitfordb
+VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+GOFLAGS := -ldflags="-s -w -X main.version=$(VERSION)"
+OS      ?= $(shell go env GOOS)
+ARCH    ?= $(shell go env GOARCH)
+
+.PHONY: all build test test-integration lint fmt clean docker patch minor major _tag
+
+all: build
+
+build:
+	CGO_ENABLED=0 GOOS=$(OS) GOARCH=$(ARCH) go build $(GOFLAGS) -o $(DIST)/$(BINARY) .
+
+test:
+	go test -race ./...
+
+# Integration test spins up a real postgres container (podman); skipped when no
+# container runtime is present.
+test-integration:
+	go test -tags integration -race -run TestIntegration -v .
+
+lint:
+	golangci-lint run ./...
+
+fmt:
+	gofmt -w .
+
+clean:
+	rm -rf $(DIST)
+
+# Build the container image locally for a smoke test.
+docker:
+	docker build --build-arg VERSION=$(VERSION) -t $(IMAGE):$(VERSION) .
+
+# Bump helpers — read the latest semver tag and create the next one, then push
+# it so the Woodpecker tag pipeline builds and publishes the image.
+_LATEST := $(shell git tag --sort=-v:refname | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$$' | head -1)
+_BASE   := $(if $(_LATEST),$(_LATEST),v0.0.0)
+_MAJ    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f1)
+_MIN    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f2)
+_PAT    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f3)
+
+patch:
+	@NEW=v$(_MAJ).$(_MIN).$(shell expr $(_PAT) + 1); \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+minor:
+	@NEW=v$(_MAJ).$(shell expr $(_MIN) + 1).0; \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+major:
+	@NEW=v$(shell expr $(_MAJ) + 1).0.0; \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+_tag:
+	git push origin $(TAG)