fix(maintenance-pool): return NotInitialized instead of panicking on missing treasury in withdraw (#488)

[urielit1313-creator]

Summary of Changes

Closes #488

1. Avoid Panic on Missing Treasury:
   • Replaced .unwrap() on mergefi_common::require_treasury::<DataKey>(&env) in contracts/maintenance-pool/src/lib.rs (withdraw) with .ok_or(Error::NotInitialized)?, matching get_treasury and standard contract initialization guards.
2. Unit Test Coverage:
   • Added test_withdraw_returns_not_initialized_if_treasury_missing to contracts/maintenance-pool/src/test.rs, verifying that if Treasury is missing from storage, client.try_withdraw cleanly returns Err(Ok(Error::NotInitialized)) instead of aborting the transaction.

Testing & Verification

• cargo test -p mergefi-maintenance-pool --lib: 43 passed; 0 failed
• cargo clippy -p mergefi-maintenance-pool --lib -- -D warnings: 0 warnings

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Bounty Payout Address (Base USDC): 0xfE777c43e4B0A24fFA1527eD520d1E7f9ECED483

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