Before exposing RI Marketplace proceeds: real-listing check, estimate labels, totals scoping #1586

#1581 (D24) records each Marketplace listing's settlement in its own table and closed #1494. These items from #1494 and the #1581 reviews must be done before any API or UI shows proceeds or totals:

• Real-listing check. Compare the poller's recorded proceeds and fee against one real closed AWS listing (needs a seller account; fix(marketplace): close RI Marketplace poller gaps (pending rows with a listing id, superseded listings, deployment coverage) #1494's "before exposing proceeds" item).
• Estimate labels. Label proceeds as estimates (D23, feat(marketplace): poll RI Marketplace listings and record proceeds and AWS fee (backend slice of #27) #1289/fix(marketplace): close RI Marketplace poller gaps (pending rows with a listing id, superseded listings, deployment coverage) #1494).
• Totals scoping. GetMarketplaceListingProceedsTotals filters by purchase id only. The future handler must scope purchase ids to the caller's account, or the method should take an account id.
• Rolling-deploy gap. A pod on the old image that settles a listing during the rollout writes no per-listing row, so totals read low until that RI is relisted. Re-run migration 000153's backfill (idempotent) or its detection query once before exposure.
• Money type. Totals are summed and returned as floats; consider an exact decimal type.
• Poll volume. Listings that AWS never prices are polled hourly per listing, and listings canceled before any poll saw them stay unsettled forever. Decide on a cutoff.