Add synchronous Midas withdrawal helper

[LukeHackett12]

Adds a stateless SyncMidasWithdrawal helper in the same style as SyncWithdrawal. The caller supplies withdrawAmount, repayAmount, useTarget, and strategy; the helper calls withdrawManager → commit → unlock.

The redeem order must already exist, its bond leg must be complete, and instant redemption must be unlocked. Facility, position manager, and fund contracts enforce their existing validation and lifecycle checks.

Only the helper and MorphoFlashLoanRequest.t.sol change, based on clean main (6998ffd). The integration test covers both withdrawal strategies, exact repayment, settlement, and flash-loan repayment using the existing MockFund.

Validation:

• CI-profile request suite: 65 passed, including 256 fuzz runs covering both withdrawal strategies.
• FOUNDRY_PROFILE=ci forge build --sizes and git diff --check pass.
• Root review, GPT-5.6-sol correctness review, and GPT-5.6-sol Ponytail pass: no remaining findings.