fix(feishu): allow ignoring all-hands mentions

[iainherd]

Summary

• add FEISHU_IGNORE_MENTION_ALL / feishu.ignore_mention_all so Feishu all-hands mentions can be ignored as bot triggers
• preserve existing default @_all admission behavior and explicit bot mentions
• document the new option in English and zh-Hans Feishu docs

Test plan

• python -m pytest tests/gateway/test_feishu_bot_admission.py tests/gateway/test_config.py tests/gateway/test_feishu.py -q
• git diff --check HEAD~1..HEAD

Closes #33723

[teknium1]

Thanks for the focused Feishu regression coverage. The premise is still present on current main: plugins/platforms/feishu/adapter.py:4331-4335 treats raw @_all as a self-mention, and the required-mention group gate consumes that result at plugins/platforms/feishu/adapter.py:4274-4275.

Problems

• The runtime change targets gateway/platforms/feishu.py:4098, but commit 5600105478ffde29d7566b45421b100eaa29c4ef moved the adapter to plugins/platforms/feishu/adapter.py; this patch cannot affect the current adapter path.
• Current Feishu-specific YAML handling belongs to _apply_yaml_config() in plugins/platforms/feishu/adapter.py:5624-5633, so the new setting needs to be carried through that plugin-owned configuration flow as part of the port.

Suggested changes

• Port the setting through the current plugin's settings, application, and _mentions_self() paths (plugins/platforms/feishu/adapter.py:377-412, 1541-1635, and 4331-4345), and port the YAML handoff to _apply_yaml_config().
• Preserve the submitted default/configured/explicit-bot-mention regression cases against the relocated adapter.

Automated hermes-sweeper review.

[teknium1]

This adapter path was moved to plugins/platforms/feishu/adapter.py by 5600105478ffde29d7566b45421b100eaa29c4ef; please port this change to the plugin adapter, where current main's _mentions_self() is at lines 4331-4345.