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

script/test

@@ -0,0 +1,17 @@
+#!/bin/sh
+# script/test: run the test suite. On failure, rerun verbosely so the
+# failing tests are visible in the output.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go test -timeout 30s -race -cover ./... || {
+        echo "--- Rerunning with -v for details ---"
+        go test -timeout 30s -race -v ./...
+        exit 1
+    }
+}
+
+main "$@"