fix: guarantee transaction record persistence

[EmeditWeb]

Problem

In transactions.service.ts (lines 101-105), persistTransactionRecord() is called with .catch() only logging. If the DB insert fails, the transaction is still submitted to Stellar but not tracked in the DB.

What To Build

1. Make persistence a prerequisite to transaction submission
2. Or implement a dead-letter queue for failed persists
3. Ensure at-least-once delivery of transaction records

Files To Touch

• src/modules/transactions/transactions.service.ts — lines 101-105

Acceptance Criteria

• Transaction not submitted if DB persist fails
• Or: failed persists queued for retry
• Build passes

Mandatory Checks

• context/ files read
• npm run build passes
• PR references this issue

[demonchant]

Hi StepFi team,I'd like to work on this issue.I have experience building backend services with Node.js and TypeScript, including transaction processing, database persistence, and reliable error-handling patterns. For this issue, I'll first review the transaction flow and the surrounding context to understand how persistTransactionRecord() interacts with Stellar transaction submission.My implementation will ensure transaction records are never silently lost. My preferred approach is to make successful persistence a prerequisite for submitting the transaction to Stellar. If the existing architecture requires asynchronous persistence, I'll implement a reliable retry/dead letter mechanism that guarantees at-least-once delivery instead of relying on fire and forget logging.I'll verify the changes by reading the required context files, ensuring all acceptance criteria are met, running npm run build, and submitting a clean PR that references this issue.I'd be happy to take this on