Update docs/PRD_MVP2.md and docs/ONCHAIN.md.
Rules:
- •Core poker-engine and WS protocol must remain stable.
- •All Web3 integration must be via adapters:
- •IdentityProvider (ERC-8004 lookup)
- •Ledger/Settlement (escrow + payout)
- •Join/buy-in payments (x402 on HTTP join endpoint only)
Deliver:
- •Migration plan from MVP1 DB ledger to MVP2 escrow
- •Minimal contract interface sketch (functions only, no full implementation needed at this stage)