refactor: clean plugin capability boundaries

src/plugin-sdk/provider-http.ts

@@ -0,0 +1,12 @@
+// Shared provider-facing HTTP helpers. Keep generic transport utilities here so
+// capability SDKs do not depend on each other.
+
+export {
+  assertOkOrThrowHttpError,
+  fetchWithTimeout,
+  fetchWithTimeoutGuarded,
+  normalizeBaseUrl,
+  postJsonRequest,
+  postTranscriptionRequest,
+  requireTranscriptionText,
+} from "../media-understanding/shared.js";