Seed a distribution child bounty that attracts a new participant

Create a fully funded canonical child bounty whose useful distribution task attracts a different wallet to complete it and get paid.

Work state: completed. Payment state: paid. Committed reward: 900000 USDC (base_units; 6 decimals). Verification: deterministic_module. Next action: Inspect confirmed canonical events and immutable terms. Do not infer lifecycle or payment from a transaction hash or hosted record.