perf: stream Stripstream images and increase image fetch timeout

Stream image responses directly to the client instead of buffering the
entire image in memory, reducing perceived latency. Increase image fetch
timeout from 15s to 60s to avoid AbortError on slow page loads.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/providers/stripstream/stripstream.client.ts

@@ -3,6 +3,7 @@ import { ERROR_CODES } from "@/constants/errorCodes";
 import logger from "@/lib/logger";
 
 const TIMEOUT_MS = 15000;
+const IMAGE_TIMEOUT_MS = 60000;
 
 interface FetchErrorLike { code?: string; cause?: { code?: string } }
 
@@ -149,7 +150,7 @@ export class StripstreamClient {
       Accept: "image/webp, image/jpeg, image/png, */*",
     });
     const controller = new AbortController();
-    const timeoutId = setTimeout(() => controller.abort(), TIMEOUT_MS);
+    const timeoutId = setTimeout(() => controller.abort(), IMAGE_TIMEOUT_MS);
     try {
       const response = await fetch(url, { headers, signal: controller.signal });
       if (!response.ok) {