Add Dead Letter Queue for Failed Webhooks

[mikewheeleer]

Implement Dead Letter Handling for Webhook Failures

Description

Persist repeatedly failed webhook deliveries for operator review and manual replay workflows.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/webhook-dead-letter-queue
• Implement changes
• Write backend code: failure sink and replay controls
• Write comprehensive tests: retry exhaustion and DLQ insertion
• Add documentation: README.md
• Include JSDoc-style comments
• Validate security assumptions

Test and commit

• Run tests
• Cover edge cases
• Include test output and security notes

Example commit message

feat(api): add dead letter queue for failed webhook deliveries

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours