Deprecated compatibility shim for callers that invoked start/2 directly.
:llm_db no longer registers an OTP application callback or starts library
processes. The catalog initializes lazily on the first public query, or
explicitly through LLMDB.load/1.
This module remains for one minor release so a direct caller can still start
the former empty supervisor. Remove direct calls and rely on the query API or
LLMDB.load/1 instead.