- Add close_system_db() function in src/db.py to cleanly close shared DB connection
- Add lifespan context manager in app/main.py to trigger shutdown on app exit
- Integrate lifespan into FastAPI app initialization
- All API tests pass (77/77)
Extractors with remote tables now write a _remote_attach table into
extract.duckdb so the orchestrator can re-ATTACH external extensions
at query time. The mechanism is source-agnostic — any connector can use it.
- Keboola extractor writes _remote_attach + creates views on kbc.*
- Orchestrator reads _remote_attach, installs extension, reads token from env
- Graceful degradation: missing token → warning, local tables still work
