Table cells contain `text` nodes directly instead of wrapping in `paragraph` — Jira rejects with INVALID_INPUT

[acreeger]

When converting markdown tables to ADF, tableCell and tableHeader nodes contain text nodes as direct children. The Jira ADF spec requires block-level children (e.g., paragraph) inside table cells.

Input:

| a | b |
|---|---|
| c | d |

Current output (invalid):

{ "type": "tableCell", "content": [{ "type": "text", "text": "c" }] }

Expected output:

{ "type": "tableCell", "content": [{ "type": "paragraph", "content": [{ "type": "text", "text": "c" }] }] }

Jira's v3 REST API returns a 400 INVALID_INPUT error when posting comments or issue descriptions containing tables. Note that validateAdf() does not catch this — it passes validation, but Jira rejects it.