Expose REST Endpoints to Trigger Document Verification and Retrieve On-Chain Confirmation Status

[mftee]

Description:
Expose the document verification workflow via REST endpoints as an independent controller layer. Triggering verification calls the StellarService to anchor the hash and persists the result.

Tasks:

• Add POST /api/documents/:id/verify — triggers StellarService.anchorHash, creates a VerificationRecord, updates document status to verified
• Add GET /api/documents/:id/verification — returns the latest verification record for a document
• Protect both routes with JwtAuthGuard
• Return 409 if the document is already in verified status

Acceptance Criteria:

• Calling verify on a document creates a VerificationRecord with a real Stellar tx hash
• The document status is updated to verified
• Calling verify on an already-verified document returns 409