Run lint and tests as Dockerfile phases built with --no-cache (closes #202)

script/check, cibuild, docker, lint, test, setup and install-precommit
are now the sneak/prompts main copies, unchanged: lint and test each
build their Dockerfile phase with --no-cache. The lint phase runs
golangci-lint from the image REPO_POLICIES.md names, with libvips-dev
from apt-get; the test phase runs the tests with a 90-second timeout;
the build stage depends on both. script/bootstrap installs the C
compiler and image libraries only with --cgo, which the test phase and
build stage pass, and refreshes the apt lists before its first apt
install. Dockerfile.lint and CHECK_EPOCH are gone, and make
docker-versioned and docker-test call the scripts. Without VERSION the
build stage still uses git describe, per issue 166.

Model: opus-5-5

Makefile

@@ -4,7 +4,7 @@ VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev
 LDFLAGS := -X main.Version=$(VERSION)
 
 # Use nix-shell to provide CGO dependencies unless they are already available
-# (e.g. inside a Docker build or an existing nix-shell).
+# (e.g. inside an existing nix-shell).
 HAS_PKGCONFIG := $(shell command -v pkg-config 2>/dev/null)
 ifdef HAS_PKGCONFIG
   NIX_RUN_PREFIX =
@@ -32,11 +32,11 @@ fmt-check:
 fmt:
 	@script/fmt
 
-# Run linter
+# Run linter (the lint phase of the Dockerfile)
 lint:
 	@script/lint
 
-# Run tests (30-second timeout)
+# Run tests (the test phase of the Dockerfile)
 test:
 	@script/test
 
@@ -64,20 +64,20 @@ docker-smoke:
 loadtest:
 	@script/loadtest
 
-# Build Docker image tagged pixad:$(VERSION) and pixad:latest
+# Build Docker image as `make docker` does, and also tag it pixa:$(VERSION)
 docker-versioned:
-	docker build --build-arg VERSION=$(VERSION) -t pixad:$(VERSION) -t pixad:latest .
+	@script/docker
+	docker tag pixa pixa:$(VERSION)
 
-# Run tests in Docker (needed for CGO/libvips)
+# Run tests in Docker, as `make test` does
 docker-test:
-	docker build --target builder --build-arg VERSION=$(VERSION) -t pixad-builder .
-	docker run --rm pixad-builder sh -c "CGO_ENABLED=1 GOTOOLCHAIN=auto go test -v ./..."
+	@script/test
 
 # Run local dev server in Docker
 devserver: docker-versioned devserver-stop
 	docker run -d --name pixad-dev -p 8080:8080 \
 		-v $(CURDIR)/config.dev.yml:/etc/pixa/config.yml:ro \
-		pixad:latest
+		pixa:latest
 	@echo "pixad running at http://localhost:8080"
 
 # Stop dev server