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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 41.92%. Comparing base (cd7218c) to head (3456ed1).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2902      +/-   ##
==========================================
- Coverage   50.68%   41.92%   -8.77%     
==========================================
  Files         110      110              
  Lines        4873     4873              
  Branches     1353     1353              
==========================================
- Hits         2470     2043     -427     
- Misses       2399     2827     +428     
+ Partials        4        3       -1     

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