fix(feishu): render markdown replies as interactive cards

[WhaleLiu-2173]

Summary

• render Feishu outbound replies as interactive cards so Markdown tables and common Markdown formatting display correctly
• keep streaming send/edit message type stable as interactive to avoid cross-type update failures
• preserve plain-text fallback when Feishu rejects the rich payload

Tests

• .venv/bin/python -m pytest tests/gateway/test_feishu.py -q -k "send_ or edit_message or build_post_payload or interactive_card_for or streaming_send_then_table_edit"
• .venv/bin/python -m pytest tests/gateway/test_stream_consumer_fresh_final.py -q
• .venv/bin/python -m pytest tests/gateway/test_stream_consumer.py::TestFinalizeCapabilityGate tests/gateway/test_stream_consumer.py::TestEditMessageFinalizeSignature -q
• git diff --check

Note: full tests/gateway/test_feishu.py still has two unrelated local webhook failures because aiohttp.web is None.

[teknium1]

Thanks for addressing the Feishu table-rendering gap. Current main confirms the underlying issue: plugins/platforms/feishu/adapter.py:4524-4534 explicitly sends table-shaped replies as plain text because post markdown tables render blank.

Problems

• The fallback migration is incomplete. The changed interactive branch still relies on _POST_CONTENT_INVALID_RE (plugins/platforms/feishu/adapter.py:166), which only matches the literal post-type validation message. The updated fallback fixture in tests/gateway/test_feishu.py:471 also returns that post-specific message despite the request becoming interactive, so it does not validate the promised fallback for an interactive-card rejection.

Suggested changes

• Verify the interactive-card validation error/code, broaden the shared predicate to that verified response shape, and cover send/edit fallback using it before relying on the plain-text fallback path.

Automated hermes-sweeper review.

[teknium1]

This now gates an interactive fallback with _POST_CONTENT_INVALID_RE, but that regex only matches the literal post-type validation message (adapter.py:166). The updated tests keep that post-specific fixture, so they do not prove an interactive-card rejection reaches the text fallback. Please use the verified interactive validation error/code and cover it here and in the edit path.