feat(#449 #467): Implement database failover pooling and SEP-10 compliance

[Sam-Rytech]

[BE-API-095] Configure Dynamic Database Failover and Read-Replica Pooling

• Implement FailoverPoolManager with primary/replica pool management
• Add automatic failover with health monitoring
• Implement read-replica routing for SELECT queries
• Add circuit breaker pattern for fault tolerance
• Expose pool health endpoints under /api/v1/pool/

[BE-W3A-113] Verify SEP-10 Compliance for Stellar Authentication

• Implement strict SEP-10 signature validation
• Add checksum validation for Stellar addresses using StrKey
• Support Freighter wallet signature formats (base64/hex)
• Implement challenge expiration and timestamp validation
• Add timing-safe string comparison for security
• Add Prisma migration for refresh_tokens table

Changes:

• backend/src/config/pool-failover.ts: FailoverPoolManager implementation
• backend/src/config/sep10-compliance.ts: SEP-10 compliance module
• backend/src/routes/pool-enhanced.ts: Enhanced pool health endpoints
• backend/migrations/20260430000001_refresh_tokens.sql: Database schema
• backend/tests/failover-pool.test.ts: Pool failover tests
• backend/tests/sep10-compliance.test.ts: SEP-10 compliance tests

Closes #449 Closes #467

[vercel]

@Sam-Rytech is attempting to deploy a commit to the mAzI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@Sam-Rytech Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits