fix(images): bound external runtime processing

tests/images.test.ts

@@ -1,3 +1,4 @@
+import type { ModuleStorage } from "@ekklesia/module-sdk";
 import sharp from "sharp";
 import { beforeEach, describe, expect, it } from "vitest";
 import { SignageError } from "../src/server/errors.js";
@@ -372,6 +373,30 @@ describe("native image ingest", () => {
     expect(store.images.size).toBe(0);
   });
 
+  it("recognizes a sanitized storage failure from the host's separate SDK copy", async () => {
+    const bucket = storage.bucket("native-images");
+    const externalError = Object.assign(new Error("The storage service could not be reached."), {
+      code: "STORAGE_PROVIDER_UNAVAILABLE",
+      name: "ModuleStorageError",
+    });
+    const externalStorage: ModuleStorage = {
+      bucket: () => ({ ...bucket, put: () => Promise.reject(externalError) }),
+      buckets: () => ["native-images"],
+    };
+
+    await expectSignageCode(
+      ingestNativeImage({
+        bytes: await makeImage({ format: "png", height: 360, width: 640 }),
+        displayName: "welcome.png",
+        expiresAt: null,
+        filename: "welcome.png",
+        storage: externalStorage,
+        store,
+      }),
+      "SIGNAGE_STORAGE_UNAVAILABLE",
+    );
+  });
+
   it("treats a race with an identical upload as a success rather than a failure", async () => {
     const bytes = await makeImage({ format: "png", height: 1080, width: 1920 });
     const first = await ingest(bytes);