Closes #246

• Batch Overflow: Fixed a logic error where the test simulator would break out of the random generation loop early on an overflow without including the overflowing element. It now ensures the contract is provided with the identical overflowing payload so that the simulator and contract fail identically.
• Vault Token Balance Overflow: Fixed a simulation limit issue where multiple maximum-allowed deposits (i128::MAX / 2) were allowed, causing the underlying USDC token balance to overflow i128::MAX. A token_sim tracker was added to prevent the test sequence from attempting deposits that breach the token standard's absolute limits.
• Type Mismatches: Fixed type mismatches in the test suite (e.g. set_allowed_depositor) where raw Addresses were passed instead of Option<Address>.
• Linting Compliance: Fixed an unused variable warning in contracts/settlement/src/test.rs, ensuring the entire workspace compiles seamlessly without any Clippy warnings.

🛡️ Security / Context

• The introduction of WithdrawEventData has no impact on existing storage or balance invariant checks, but provides critical context for indexing infrastructure.
• batch_deduct now formally requires an unpaused state, hardening the vault's emergency circuit breaker against batch deductions during an incident.

Closes(#246)