Adopt scripts-to-rule-them-all: script/ entrypoints, Makefile shims

script/fmt

@@ -0,0 +1,27 @@
+#!/bin/sh
+# script/fmt: format all files (writes).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Regenerate mfer/mf.pb.go from mfer/mf.proto if it is missing or stale
+# (mirrors the old Makefile prerequisite; the generated file is
+# committed, so this is normally a no-op).
+ensure_pb() {
+    if [ ! -f mfer/mf.pb.go ] ||
+        [ -n "$(find mfer/mf.proto -newer mfer/mf.pb.go 2>/dev/null)" ]; then
+        (cd mfer && go generate .)
+    fi
+}
+
+main() {
+    cd "$ROOT"
+    ensure_pb
+    gofumpt -l -w mfer internal cmd
+    golangci-lint run --fix
+    # prettier is best-effort, as in the old Makefile (- prefix)
+    prettier -w *.json || true
+    prettier -w *.md || true
+}
+
+main "$@"