fix(cli): wrap streaming-phase download timeout with friendly message

downloadVerifiedBinary only wrapped isTimeoutError around the fetch()
catch, so a 15-minute timeout firing while pipeline() streamed the
response body re-threw the raw "TimeoutError: The operation timed out."
Mirror the wrap into the pipeline catch after cleaning up the partial
file, matching the connection-phase message.

Fixes #6822

packages/coding-agent/test/update-cli.test.ts

@@ -465,6 +465,31 @@ describe("update-cli release binary integrity", () => {
 		expect(await Bun.file(targetPath).exists()).toBe(false);
 	});
 
+	it("wraps a timeout during body streaming with a friendly message", async () => {
+		const dir = await makeTempDir();
+		const targetPath = path.join(dir, binaryName);
+		const body = new ReadableStream<Uint8Array>(
+			{
+				pull(controller) {
+					controller.enqueue(new Uint8Array(1));
+					controller.error(new DOMException("The operation timed out.", "TimeoutError"));
+				},
+			},
+			{ highWaterMark: 0 },
+		);
+
+		await expect(
+			downloadVerifiedBinary({
+				url,
+				targetPath,
+				expectedSize: Buffer.byteLength(content),
+				expectedDigest: digest,
+				fetchImpl: async () => new Response(body),
+			}),
+		).rejects.toThrow("Timed out downloading release binary after 15 minutes");
+		expect(await Bun.file(targetPath).exists()).toBe(false);
+	});
+
 	it("removes downloads whose size or digest does not match", async () => {
 		const dir = await makeTempDir();
 		const targetPath = path.join(dir, binaryName);