Stub adapter that validates constructor args and exposes the public
shape (IncrementRefCount / DecrementRefCount / GetRenderData / Dispose).
Real ObjectMeshManager init is deferred to Task 9 — for now methods
no-op so call sites can wire the adapter without behavioral effect.
IWbMeshAdapter interface enables mocking in subsequent tasks
(LandblockSpawnAdapter tests in Task 11 need it).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
