cultmesh-browser: drop the post-read abort check from fetchVerifiedChunk

No await separates the read from the return there, and the failure race already rejects an abort that lands during the chunk hash; a mutant deleting the line survived every test because no window exists to pin.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/cultmesh-browser/src/content.ts

@@ -152,6 +152,5 @@ export async function fetchVerifiedChunk(endpoint: string, chunkHash: string, si
   requireWebCrypto();
   const slot = allocate(sizeBytes);
   await readChunks(r, [{ url: chunkUrl(endpoint, hash, chunkRecordKey(hash)), hash, slot }]);
-  r.caller?.throwIfAborted();
   return slot;
 }