Keep a guest community logo on review and on the published rule.

Sign-in was clearing the staged file before it uploaded, and review only read the server URL, so a chosen logo disappeared after the upload step.

lib/create/uploadToServer.ts

@@ -28,8 +28,8 @@ function reasonFromUnknown(value: unknown): CreateFlowUploadValidationReason | n
 }
 
 /**
- * Authenticated multipart upload to `POST /api/uploads`.
- * Caller must have a session cookie (same-origin fetch).
+ * Multipart upload to `POST /api/uploads`.
+ * `communityAvatar` is accepted for a guest; other purposes need a session.
  */
 export async function uploadCreateFlowFile(
   file: File,