[Issue #274] Add flash-loan mitigation and price manipulation guard

[Quanwritescodes]

Summary

Implements the escrow protections requested in issue #274.

Changes

• Adds persistent price-feed state with rolling cumulative samples.
• Requires a minimum of 10 price samples before applying the TWAP drift guard.
• Suspends escrow operations when the latest price deviates more than 5% from TWAP.
• Blocks price updates in the same ledger.
• Adds per-depositor ledger spacing to reject same-ledger and consecutive-ledger replay patterns.
• Applies the guards to escrow deposits and releases.
• Preserves existing escrow storage versioning and token transfer behavior.

Acceptance criteria

• Same-ledger price updates are rejected.
• Flash-loan-style repeated actions are blocked by ledger spacing.
• TWAP protection activates after the required sample window.
• Price-feed suspension occurs beyond the 5% drift threshold.

Validation

• git diff --check passes.
• Full Rust validation remains environment-blocked by the local rustup target metadata and was not claimed as passing.

Closes #274

[vercel]

@Quanwritescodes is attempting to deploy a commit to the milah's projects Team on Vercel.

A member of the Team first needs to authorize it.