The no-SDK fallback guards check '"Name" in globals()' — correct on
main where a failed module-level import leaves those names undefined,
but the deferred-import port pre-binds every SDK name to None, so the
guard was always true and the fallback paths called .builder() on None
(AttributeError) wherever lark_oapi isn't installed. Local runs passed
because lark IS installed here; CI's default env has no feishu extra.
Rewrote all 14 guards to 'is not None', which is correct under both
conditions. Verified by simulating CI with a lark-blocking meta_path
hook: 74 passed, 18 skipped (the skipUnless set), zero failures.
e80b7aeda1