v0.4.1

Changes

• Return Feishu card callback responses immediately so the client does not wait for chat acknowledgement or Codex processing.
• Move card acknowledgement delivery and Codex resume work to background execution.
• Prefer visible chat messages for card-action text replies.

Verification

• python3 -m unittest -v test_feishu_codex_bridge.py
• python3 -m py_compile feishu_codex_bridge.py test_feishu_codex_bridge.py
• git diff --check