refactor: dedupe media and request-body test scaffolding

src/test-helpers/ssrf.ts

@@ -0,0 +1,14 @@
+import { vi } from "vitest";
+import * as ssrf from "../infra/net/ssrf.js";
+
+export function mockPinnedHostnameResolution(addresses: string[] = ["93.184.216.34"]) {
+  return vi.spyOn(ssrf, "resolvePinnedHostname").mockImplementation(async (hostname) => {
+    const normalized = hostname.trim().toLowerCase().replace(/\.$/, "");
+    const pinnedAddresses = [...addresses];
+    return {
+      hostname: normalized,
+      addresses: pinnedAddresses,
+      lookup: ssrf.createPinnedLookup({ hostname: normalized, addresses: pinnedAddresses }),
+    };
+  });
+}