[config] fork.toml liquidator contract_address is zero — executor fails cryptically on first opportunity

[obchain]

Refs #52

File: config/fork.toml

Problem

fork.toml likely leaves liquidator.bnb.contract_address at 0x0 since no deployment exists on the fork. Once the pipeline produces an opportunity, executor tries to build calldata for address(0), fails inside TxBuilder with opaque error.

Fix options

A. Deploy CharonLiquidator to anvil fork as part of anvil_fork.sh script; write deployed address to fork.toml dynamically.

B. Omit [liquidator] section entirely in fork.toml so read-only mode kicks in (PR #51 pattern).

Prefer A for Path B demo (needs full pipeline). Add forge create contracts/src/CharonLiquidator.sol:CharonLiquidator --rpc-url http://127.0.0.1:8545 ... to anvil_fork.sh after fork boots.

[obchain]

Fixed on feat/24-anvil-fork (4969bb7): dropped the [liquidator.bnb] block with its address(0) placeholder. Omission flips the CLI onto the read-only arm in run_listen (scanner + metrics only), matching the pattern testnet.toml uses for Chapel. A replacement comment block documents how to add the section back after running forge create against the local anvil.