test: cover CCTP replay rejection in cross-chain mock

[m0n3r0]

Summary

This PR tightens local cross-chain CCTP test coverage by making the unit mock reject replayed encoded messages and adding a regression test for replaying an already-relayed balance update.

Changes

• Tracks processed encoded messages in CCTPMessageTransmitterMock.
• Adds a cross-chain test that processes a balance update once, then directly attempts to relay the same encoded CCTP message again and expects rejection.
• Preserves existing CCTP sender/domain/finality and pending-state behavior.

Testing

• IS_TEST=true pnpm exec hardhat test test/strategies/crosschain/cross-chain-strategy.js --grep "direct replay" --bail
• IS_TEST=true pnpm exec hardhat test test/strategies/crosschain/cross-chain-strategy.js --grep "Should mint USDC to master strategy|direct replay|Should emit a BalanceCheckIgnored|Should fail on deposit if a previous one has not completed" --bail
• IS_TEST=true pnpm exec hardhat test test/strategies/crosschain/cross-chain-strategy.js

Notes

Defensive regression coverage only; no sensitive vulnerability details are included.