Added explicit context checks at critical points:
1. After extraction completes - logs error if context was cancelled
2. Before database restore loop starts - catches premature cancellation
This helps diagnose issues where all database restores fail with
'context cancelled' even though extraction completed successfully.
The user reported this happening after 4h20m extraction - all 6 DBs
showed 'restore skipped (context cancelled)'. These checks will log
exactly when/where the context becomes invalid.
Alexander Renz
9200024e50