Production hardening backlog

[wauputr4]

Goal

Track hardening needed before serious production pilots.

Scope

• Queue workers.
• Retry and idempotency improvements.
• Webhook signature verification.
• Request replay protection.
• Observability hooks.
• Deployment examples.
• Permission and approval workflows.

Acceptance Criteria

• Hardening work is split into smaller issues before implementation.
• Security docs are updated as behavior changes.
• Production readiness boundaries are explicit.