test: align media defaults metadata fixture

src/media-understanding/defaults.test.ts

@@ -77,6 +77,18 @@ vi.mock("../plugins/plugin-registry.js", () => ({
     plugins: mediaMetadataPlugins,
     diagnostics: [],
   }),
+  loadPluginRegistrySnapshotWithMetadata: () => ({
+    source: "derived",
+    snapshot: { plugins: [] },
+    diagnostics: [],
+  }),
+}));
+
+vi.mock("../plugins/manifest-contract-eligibility.js", () => ({
+  loadManifestMetadataSnapshot: () => ({
+    index: { plugins: [] },
+    plugins: mediaMetadataPlugins,
+  }),
 }));
 
 import {