Salvage of #57657, ported onto the plugin layout (the adapter moved
from gateway/platforms/feishu.py to plugins/platforms/feishu/adapter.py
since the PR's base). lark_oapi takes seconds to import and holds the
GIL doing it; the module-level import made every gateway boot pay that
cost even with Feishu unconfigured.
- _load_lark_oapi() with double-checked locking binds the SDK globals
on first use; connect() and _standalone_send() call it via
asyncio.to_thread so the loop never blocks on the import.
- probe_bot() also calls _load_lark_oapi() (sync context) so the SDK
probe path is preserved rather than silently degrading to the HTTP
fallback before a first connect.
- check_feishu_requirements() is install-only and no longer rebinds
globals; test_feishu.py gets a setUpModule that binds them eagerly
for tests that inject fake clients.
Includes the dedicated lazy-import test file (check-does-not-import,
connect-loads-on-worker-thread).
b51c4e6a78