GFM tables flattened to sequential `<p>` blocks on sync

Affected: Plane Cloud, official GitHub integration. See also: meta-issue on destructive overwrite (issue 01).

Symptom

GitHub-Flavoured Markdown tables in an issue or comment body are flattened during sync round-trip. Row/column relationships and the header distinction are lost; each cell becomes its own <p> block.

Input (GH markdown):

| col_a | col_b |
|---|---|
| 1 | foo |
| 2 | bar |

Pushed back to GH markdown:

col_a

col_b

1

foo

2

bar

Impact

GFM tables are widely used and clearly documented. Losing them loses row/column relationships and the header row entirely, leaving the reader to guess which cells were paired.

Ask

Preserve markdown table syntax through the round-trip.

Reproduction

1. Connect a GitHub repo to a Plane workspace via the official GitHub integration. Set sync to bidirectional.
2. Create a GitHub issue whose body contains a GFM table. Apply the Plane label.
3. To exercise the destructive Plane→GH push, follow the trigger recipe in meta-issue 01. Compare the resulting body against the original via userContentEdits.

Reproduce the bidirectional official GitHub integration flow with a labeled issue containing a GFM table, then compare the original and pushed body via userContentEdits. Trace the markdown conversion path used by the integration; done means the round trip retains table syntax, row/column relationships, and the header distinction.