feat: deterministic sorting, failure fixtures, safe ownership transfer, and rollback verification

[rubbathabrahband]

Summary of Changes

This PR addresses issues #286, #287, #288, and #289 across Trellis-API:

1. Deterministic Sorting for Mixed-Status Records and Events (Trellis-API: Add deterministic sorting for mixed-status records and events #286):

   • Added DeterministicSorter implementing a multi-tier comparator: status priority hierarchy, timestamp normalization, and unique tie-breaking ID.
   • Built URL-safe base64 cursor pagination utilities (encodeCursor, decodeCursor, paginate) ensuring zero page drift and no duplicated items across page boundaries.
   • Full test suite in src/common/sorting/deterministic-sorter.spec.ts.

2. Fixture Generators for Rare Failure & Recovery Paths (Trellis-API: Create fixture generators for rare failure and recovery paths #287):

   • Created FailureFixtureGenerator in src/common/fixtures/failure-fixture-generator.ts providing reproducible test fixtures for rare distributed edge cases:
     • Deep ledger reorganizations with orphaned transactions and diverging hashes.
     • Sequence/nonce collisions resulting in txBAD_SEQ.
     • Malformed XDR payloads (truncated, invalid base64, mismatched passphrases, corrupted signatures).
     • Partial database commits with compensating transaction instructions.
     • Dead-letter queue spills after maximum retry exhaustion.
     • Tampered cryptographic audit trails.
   • Full test suite in src/common/fixtures/failure-fixture-generator.spec.ts.

3. Safe Ownership Transfer with Pending Acceptance and Expiry (Trellis-API: Implement safe ownership transfer with pending acceptance and expiry #288):

   • Implemented two-step OwnershipTransferService requiring explicit recipient acceptance before resource ownership reassignment.
   • Built-in expiration window (default 72h) and initiator cancellation capabilities.
   • Exposed REST API via OwnershipTransferController and registered in AppModule.
   • Comprehensive test suite in src/core/ownership/ownership-transfer.service.spec.ts.

4. Rollback Verification After Failed Migrations or Deployments (Trellis-API: Add rollback verification after failed migrations or deployments #289):

   • Built RollbackVerificationService executing pre- and post-rollback invariant checks:
     • Migration lock clearance.
     • Core table schema presence verification across 9 required entities.
     • Referential integrity and orphaned foreign key auditing.
     • Row count data continuity.
     • Active database connection smoke queries.
   • Generates actionable verdicts (VERIFIED, WARNING, FAILED), discrepancy lists, and traffic-blocking guardrails.
   • Unit test suite in src/infrastructure/disaster-recovery/rollback-verifier.service.spec.ts.

5. Operational Documentation:

   • Documented architecture, multi-tier comparator rules, failure fixture definitions, two-step transfer state machines, and rollback verification runbooks in docs/MIGRATION_ROLLBACK_AND_DATA_RELIABILITY.md.
   • Updated README.md with links to the reliability guide.

Closes #286
Closes #287
Closes #288
Closes #289

[github-actions]

Code Review & Auto-Merge — @dorismaduegbunam 🚀

Thank you @rubbathabrahband for your contribution!

• PR Title: feat: deterministic sorting, failure fixtures, safe ownership transfer, and rollback verification
• Author: @rubbathabrahband
• Branch: feat/issues-286-289-deterministic-sorting-fixtures-ownership-rollback -> main
• Linked Issues: Closes Trellis-API: Add deterministic sorting for mixed-status records and events #286, Closes Trellis-API: Create fixture generators for rare failure and recovery paths #287, Closes Trellis-API: Implement safe ownership transfer with pending acceptance and expiry #288, Closes Trellis-API: Add rollback verification after failed migrations or deployments #289
• Status: Approved & Merged into main.

Verified code changes and repository requirements. Merging pull request.