Isolate withdrawal liquidity lookup failures

[hellojason3]

Summary

• keep an ERC20 liquidity lookup failure scoped to the affected withdrawal
• continue validating and settling the remaining withdrawals in the batch
• retain the failed withdrawal in durable pending state for retry and audit

Root cause

A token address from a different destination chain caused balanceOf decoding to fail. The error used ?, so one malformed withdrawal aborted the entire submit_batch call and prevented unrelated pending withdrawals from being processed.

Verification

• cargo fmt --package psy_relayer_cli -- --check
• cargo test -p psy_relayer_cli --bin psy_relayer_cli (121 passed)
• git diff --check

The historical malformed withdrawal was quarantined operationally before this change; this PR prevents the same failure class from blocking otherwise valid work.