feat(feishu): add configurable reply-in-thread behavior

[leowzz]

Summary

• add feishu.reply_in_thread for Feishu/Lark
• when enabled, replies to top-level messages start a topic
• keep replies inside existing topics regardless of the setting
• preserve the existing default (false) for backward compatibility
• add configuration and adapter regression tests
• document the option in the English and Chinese Feishu guides

Scope

This PR only introduces the configurable behavior. The Feishu API validation and delayed-job thread-delivery fixes are submitted separately.

Testing

• scripts/run_tests.sh tests/gateway/test_feishu.py tests/gateway/test_config.py tests/gateway/test_run_progress_topics.py -q --tb=short
• 353 tests passed
• git diff --check

[teknium1]

Thanks for the focused Feishu configuration addition. Current main still derives reply_in_thread only from metadata.thread_id in plugins/platforms/feishu/adapter.py:4623; the normal outbound response path supplies a reply anchor at gateway/platforms/base.py:5097-5102. The proposed flag therefore changes the intended top-level reply behavior while retaining existing-topic routing. Its config test matches the established top-level config bridge in gateway/config.py:1280-1283, and the English and Chinese guide updates document the opt-in default clearly.

Automated hermes-sweeper review.