Bounty: Cancel (poster refund) ($0.002/call)

Poster reclaims the reward of a bounty nobody completed: POST {id}. Full refund, no fee. Poster-only. Works while OPEN, or while CLAIMED-but-stale (the claimer ghosted past the claim TTL). Not once a result is SUBMITTED — approve that instead.

Paid endpoint: $0.002 per call via the x402 protocol (USDC on Base). An unpaid request returns 402 with payment requirements in the PAYMENT-REQUIRED response header; attach payment and retry.