Check bank-match pipeline progress

See how many bank-feed rows are sitting in each pipeline stage. Useful after calling /populate/: poll this every few seconds to know when the matcher is done.

The pipeline is still working while any of these are non-zero: unprocessed, awaiting_ai, ai_in_progress. Once all three hit zero, you're done, and the terminal stages (ai_suggested, deterministic_suggested, matched, ai_no_match, no_match, excluded) hold the outcome.

Expired bank-feed rows are excluded so the numbers reflect real pending work.