fix(attachment-local): keep reference field order stable for logged fixtures

The canonical ref serializes mediaType, width, height, bytes in the order the
pre-canonicalization store used, so existing session-log fixtures and logged
histories keep byte-identical reference JSON.

packages/attachment/attachment-local/src/store.ts

@@ -203,9 +203,9 @@ export async function saveImageFile(
     ref: {
       attachmentId: AttachmentId(`sha256:${sha256}`),
       mediaType: canonical.mediaType,
-      bytes: canonical.data.byteLength,
       width: canonical.width,
       height: canonical.height,
+      bytes: canonical.data.byteLength,
       ...(name !== undefined ? { name } : {}),
     },
     source: metadata,