BIP84 derivation of per-user P2WPKH addresses and the pool address from the encrypted master xprv (app/wallet/hd.py, keystore.py), the PLM mainnet chain params (plm_network.py), and PSBT construction for bets/ payouts/withdrawals with change-output and fee-estimation logic (psbt_builder.py). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>