bring the repo up to org standards

Adopt the standard tooling: a Makefile of thin shims over a full
scripts-to-rule-them-all `script/` set, the canonical `.golangci.yml`
vendored byte-identical from `sneak/prompts`, docker-only linting via
`Dockerfile.lint`, a `Dockerfile` and Gitea workflow that gate every
push, and prettier/editorconfig/dockerignore config.

`make build` pointed at a `cmd/dcfinfo` that is not in the tree and
could never have succeeded; this repo is a library, so `build` is now
the compile check over every package.

Clear the 57 findings the canonical linter config reports on `pkg/dcf`.
Two were real: `findDCFMountPoints` checked a never-assigned `erro`
instead of the error from `findAllMountPoints`, discarding it, and
`privatePath` was computed twice so the first computation was dead.
Mountpoint selection otherwise behaves exactly as before; the defects
that survive are filed as issue #6, not fixed here.

Rename `DCFStore` to `Store` and `DCFObject` to `Object` (with its
`DCFStoreRoot` field to `StoreRoot`), which revive's stutter rule
requires and which the `fs.FS` rework in issue #4 will build on.

Replace the placeholder test with tests over the exported surface.
The filesystem walk stays uncovered: it is reachable only through
`GetDCFStores`, which needs real mounted media.

README keeps its content, reorganised into the required sections and
gaining Entrypoints.

(closes #1)

Makefile

@@ -1,14 +1,50 @@
-default: test
+.PHONY: bootstrap setup test lint fmt fmt-check check build deps docker cibuild clean hooks
+
+# Every target is a thin shim over script/. The scripts are the real
+# entrypoints: they carry the project-specific knowledge (flags,
+# timeouts, docker-only linting) that a raw `go test` or `golangci-lint`
+# invocation silently bypasses. Never call the underlying tools
+# directly.
+.DEFAULT_GOAL := check
+
+bootstrap:
+	@script/bootstrap
+
+setup:
+	@script/setup
 
 test:
-	go test -v ./...
+	@script/test
 
-run: build
-	DEBUG=1 ./dcfinfo
+lint:
+	@script/lint
 
+fmt:
+	@script/fmt
+
+fmt-check:
+	@script/fmt-check
+
+check:
+	@script/check
+
+# This repo is a library: there is no cmd/ and nothing to link, so
+# `build` is the compile check over every package.
 build:
-	go env -w CGO_ENABLED="0"
-	cd cmd/dcfinfo && go build -o ../../dcfinfo
+	go build ./...
+
+deps:
+	go mod download
+	go mod tidy
+
+docker:
+	@script/docker
+
+cibuild:
+	@script/cibuild
 
 clean:
-	rm -f dcfinfo
+	go clean ./...
+
+hooks:
+	@script/install-precommit