fix(feishu): send markdown tables as post instead of forcing plain text

[xielevi]

Problem

When Hermes sends a Feishu message containing a markdown table, _build_outbound_payload detects the table via _MARKDOWN_TABLE_RE and forces msg_type="text". This renders the table as raw pipe-delimited text (| col | col |), which is strictly worse than any alternative.

Related issues: #21866, #27469

Fix

Remove the table→text fallback and let tables take the same post path as other markdown content. The _MARKDOWN_TABLE_RE regex now triggers the post branch (alongside _MARKDOWN_HINT_RE) instead of the text fallback.

# Before
if _MARKDOWN_TABLE_RE.search(content):
    text_payload = {"text": content}
    return "text", json.dumps(text_payload, ensure_ascii=False)
if _MARKDOWN_HINT_RE.search(content):
    return "post", _build_markdown_post_payload(content)

# After
if _MARKDOWN_HINT_RE.search(content) or _MARKDOWN_TABLE_RE.search(content):
    return "post", _build_markdown_post_payload(content)

Safety

The existing send_message() method already catches post payload rejections from the Feishu API (_POST_CONTENT_INVALID_RE) and falls back to plain text with _strip_markdown_to_plain_text(). This safety net remains intact — if the post payload is rejected, the user still gets the message, just without formatting.

Testing

Verified with the following markdown elements in Feishu client — all render correctly:

Element	Status
Headers (H1-H3)	✅
Bold / Italic / Strikethrough	✅
Ordered / Unordered lists	✅
Code blocks (fenced)	✅
Inline code	✅
Blockquotes	✅
Tables	✅
Links	✅
Horizontal rules	✅

Notes

• For users with hermes-lark-streaming plugin installed, this code path is typically bypassed (streaming cards set already_sent=True), but the fix ensures correct behavior for all users regardless of plugin setup.
• The more comprehensive solution proposed in [feishu] Unified fix for markdown rendering: inbound escaping + GFM table → Card 2.0 #27469 (using msg_type="interactive" Card 2.0 for tables) would be a separate enhancement. This PR is the minimal fix that removes the actively harmful fallback.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #27922 — this is part of the long-standing Feishu markdown-table rendering cluster (meta #27469). At least six open PRs (#27922, #28030, #31410, #34181, #36637, #38867) apply the same fix: remove the _MARKDOWN_TABLE_RE→text force-fallback in _build_outbound_payload() and route tables through the post path. #27922 is the earliest open PR with this approach and is treated as canonical. Flagging the cluster for a maintainer to pick one.

[xielevi]

Closing as duplicate of #27922. Same fix (remove _MARKDOWN_TABLE_RE→text fallback, route tables through post path) already proposed in at least 6 open PRs (#27922, #28030, #31410, #34181, #36637, #38867). #27922 is canonical.