Bring the repo up to the standard layout (closes #1)

Adds the canonical .gitignore, .dockerignore and .editorconfig; the
first two also name this repo's build output, root-anchored so
cmd/bsdaily/ stays in. The Dockerfile gains a lint phase on the
golangci-lint image already pinned and a test phase on the Debian Go
image with sqlite3 and zstd; the build stage copies a file from each,
so a plain docker build cannot skip them. script/lint and script/test
build their phase uncached and tagged; script/cibuild, script/docker
and the CI workflow are the canonical copies. Nothing installs
golangci-lint on the host. REPO_POLICIES.md is re-vendored.

.golangci.yml and the lint cleanup: #6
Judgement call: .gitignore adds Go build output, per the Go styleguide.

Model: opus-5-5

Dockerfile

@@ -1,9 +1,9 @@
-# Lint stage
+# Lint phase. The linter is invoked directly rather than through `make
+# lint` or `script/lint`, which are themselves a docker build and would
+# recurse into a daemon that does not exist in a build step.
 # golangci/golangci-lint:v2.12.2-alpine
 FROM golangci/golangci-lint:v2.12.2-alpine@sha256:91b27804074a0bacea298707f016911e60cf0cdbc6c7bf5ccacb5f0606d18d60 AS lint
 
-RUN apk add --no-cache make build-base
-
 WORKDIR /src
 
 # Copy go mod files first for better layer caching
@@ -13,22 +13,42 @@ RUN go mod download
 # Copy source code
 COPY . .
 
-# Run formatting check and linter
-RUN make fmt-check
-RUN make lint
+RUN golangci-lint run ./...
 
-# Build stage
+# Test phase, invoking `go test` directly for the same reason. -race
+# needs cgo and so a C compiler, which the Debian Go image ships and the
+# alpine one does not. The tool shells out to sqlite3, zstdmt and
+# zstdcat, so tests that run it need them installed.
+# golang:1.26.4-trixie, 2026-10-05
+FROM golang:1.26.4-trixie@sha256:68b7145ec43d1820b9a56704554b53d1520aa2a15cb5233e374188a31b2a1bce AS test
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends sqlite3 zstd \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /src
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+RUN go test -timeout 90s -race -cover ./... || \
+    { echo "--- Rerunning with -v for details ---"; \
+      go test -timeout 90s -race -v ./...; exit 1; }
+
+# Build stage. Nothing is wanted from either phase above; the copies
+# are what make BuildKit build them first, so this stage cannot run
+# unless lint and test passed. A plain `docker build .` builds only the
+# last stage and what it depends on, so the runtime stage stays last.
 # golang:1.26.4-alpine
 FROM golang:1.26.4-alpine@sha256:3ad57304ad93bbec8548a0437ad9e06a455660655d9af011d58b993f6f615648 AS builder
 
-# Depend on lint stage passing
 COPY --from=lint /src/go.sum /dev/null
+COPY --from=test /src/go.sum /dev/null
 
 ARG VERSION=dev
 
-# Install build deps plus the sqlite3 and zstd CLIs the tests/tool shell out to
-RUN apk add --no-cache make build-base sqlite zstd
-
 WORKDIR /src
 
 # Copy go mod files first for better layer caching
@@ -38,9 +58,6 @@ RUN go mod download
 # Copy source code
 COPY . .
 
-# Run tests
-RUN make test
-
 # Build (pure Go, no CGO required since we use modernc.org/sqlite)
 RUN CGO_ENABLED=0 go build -o /bsdaily ./cmd/bsdaily