Last return-type variant in the matrix. JNI's jobject is a pointer
(LocalRef) — sx's `*void` maps to LLVM `ptr` directly. CallObjectMethod
is at vtable slot 34. IR snapshot captures today's `ret ptr undef`.
Next commit adds the `.ptr => Jni.CallObjectMethod` arm.
LocalRef lifetime: the returned jobject is a JNI LocalRef bounded by
the native frame. Chains of calls within one frame consume LocalRefs
inline; calls that need to escape the frame should be promoted via
`NewGlobalRef` (already wired in the slot-interning path). Step 1.22
doesn't introduce automatic cleanup — chess use consumes objects
inline, matching the pattern in sx_android_jni.c.
908b6d19a3