Support ComposableCoW v2 ConditionalOrderRemoved event

[mfw78]

Feature request: index the new ConditionalOrderRemoved event from the updated ComposableCoW contract to clean up watches when orders are removed on-chain.

Module: modules/twap-monitor

[ribeirojose]

Scoping note: the cowprotocol crate (cowdao-grants/cow-rs @ 0.1.0) mirrors the composable-cow v1 interface and has no ConditionalOrderRemoved binding — mirror it locally in twap-monitor's abi module (like the existing ConditionalOrderCreated handling) rather than waiting on an SDK release. Scope: event decode + watch/gate delete + a new [[subscription]] in modules/twap-monitor/module.toml. Best sequenced after #48 and #121 (same strategy.rs).

[mfw78]

Landed via #472 (squash-merged into dev/m1). Closing manually since the merge target is not the default branch.