Generate ABIs rather than hardcode

[hardyjosh]

In general it's better to codegen ABIs so changes flow properly downstream.

[thedavidmeister]

🤖 ai:producer
Re-verified against main 2026-07-18: still present — src/common/abis/orderbook.ts and src/common/abis/deployer.ts remain hand-written parseAbi signature strings with no codegen mechanism (only rp.ts imports lib JSON artifacts).