chore: import upstream snapshot with attribution

showcase/scripts/verify-deploy.drivers.shell.ts

@@ -0,0 +1,24 @@
+import type { ProbeTarget } from "./verify-deploy";
+import type { ProbeOutcome } from "./verify-deploy.drivers";
+import { probeBaseline } from "./verify-deploy.drivers.baseline";
+
+/**
+ * Feature-level verifier for the Next.js `shell` service (the main
+ * showcase shell). Per spec §3.5 ("200 ≠ healthy") the eventual goal
+ * is to load the page and assert a known DOM string + a known network
+ * call. The baseline implemented here is the floor every driver must
+ * meet:
+ *   1. Railway deployment-SUCCESS for the resolved env (GraphQL).
+ *   2. HTTP 200 on `https://<host>/` (the shell's Next.js root).
+ *
+ * Driver-specific DOM + network-call extensions can compose on top of
+ * `probeBaseline` (run after a green baseline) when the per-driver
+ * micro-tasks land. Until then, this baseline is the agreed completion
+ * bar — and crucially, NO driver remains a "not yet implemented" stub.
+ */
+export async function probeShell(target: ProbeTarget): Promise<ProbeOutcome> {
+  return probeBaseline(target, {
+    driverLabel: "shell",
+    healthcheckPath: "/",
+  });
+}