Fix Feishu group mention config

[timmyagentic]

Fixes #15226

Summary

• Bridge Feishu group reply settings from config.yaml into runtime PlatformConfig.extra.
• Add require_group_mention support in the Feishu adapter with a secure default of true.
• Coerce common boolean representations so string values like "false" work as expected.
• Add regression tests for config bridging and unmentioned group message routing.

Verification

pytest tests/gateway/test_feishu.py tests/gateway/test_config.py -q
218 passed

Notes

This keeps group policy checks in place before accepting unmentioned group messages. Disabling mention requirements only routes messages when the existing sender/chat policy allows them.

[teknium1]

Thanks for the focused Feishu regression report and tests. This is already implemented on current main through the later Feishu admission-policy work, so this PR is now redundant. This is an automated hermes-sweeper review.

• Merged PR feat(feishu): operator-configurable bot admission and mention policy #18208 closed the linked issue Feishu group messages ignore require_group_mention=false from config.yaml #15226 and introduced the supported require_mention policy (d83b41c9e73670396b6b0815913e744023f0b018).
• plugins/platforms/feishu/adapter.py:1600-1602 resolves the configurable mention setting with a secure default; plugins/platforms/feishu/adapter.py:4270-4282 preserves group-policy checks and only requires a mention when configured.
• tests/gateway/test_feishu_bot_admission.py:92-111 and :335-343 cover disabled mention gating and admission of an unmentioned group message under an open policy.
• The adapter was subsequently migrated from the PR's former gateway/platforms/feishu.py location to plugins/platforms/feishu/adapter.py.