- Add _init_memory_db() path using Base.metadata.create_all + StaticPool
since Alembic migrations don't work with in-memory SQLite (each
connection gets its own separate database)
- Call init_mime_types() at module load in metadata_extract so custom
types like application/safetensors are always registered
Amp-Thread-ID: https://ampcode.com/threads/T-019cbb5f-13d1-7429-8cfd-815625c4d032
Co-authored-by: Amp <amp@ampcode.com>