fix docker stream backpressure (#1445)

src/lib/server/node-readable-stream.ts

@@ -0,0 +1,9 @@
+import { Readable } from 'node:stream';
+
+/**
+ * Convert a Node readable to a Web stream while preserving Node backpressure.
+ * Cancellation and source errors are forwarded by Node's native adapter.
+ */
+export function toWebReadableStream(source: Readable): ReadableStream<Uint8Array> {
+	return Readable.toWeb(source) as ReadableStream<Uint8Array>;
+}