MRWK bounty: paid bounty index reconciliation

Acceptance

What has to be true

Focused docs PR that reconciles docs/paid-bounties.md with public proof-backed missing payment rows. Each row must include date, bounty link, accepted work link, recipient, amount, and proof link, with docs smoke evidence. Duplicate rows, broad docs rewrites, stale links, unverifiable payouts, unrelated churn, price claims, investment claims, or fabricated payout claims do not qualify.