Build transaction pre-compliance filter before provider send

[pchieneye]

Summary

Implements transaction pre-compliance filter that checks AML compliance before sending transactions to the mobile money provider.

What Changed

• Created PreComplianceService to gate transactions through AML monitoring
• Integrated pre-compliance check into worker transaction processing flow (before initiatePayment() and sendPayout() calls)
• Non-compliant transactions are blocked and tagged with aml-flagged and compliance-blocked
• Added AML alert deduplication by transaction ID to prevent duplicate records

Files Modified

• src/compliance/preCompliance.ts - New PreComplianceService class
• src/compliance/__tests__/preCompliance.test.ts - Unit tests (2 passing)
• src/queue/worker.ts - Integrated pre-compliance gate
• src/models/amlAlert.ts - Added findByTransactionId() deduplication method
• src/services/aml.ts - Enhanced alert persistence with deduplication

Testing

• Unit tests written and passing (2/2)
• Pre-compliance check runs at transaction progress 20 for both deposit and withdraw flows
• Blocked transactions are tagged and logged with compliance reasons in metadata

Closes sublime247#592