stabilize.test.ts used `data-align="center"` as proof the convergence pass
materialized the drawio node. Since this PR correctly stops emitting the
schema-default center align in the media builders, that marker is no longer a
reliable convergence proof. Assert on the stable canonical markers instead —
`data-type="drawio"` + `data-src="/d.drawio"` — which are always materialized
regardless of the align default. The fixpoint assertion (file2 === file1) is
unchanged; round-trip stays byte-stable.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
agent_coder
ccee32cb0b