Create infrastructure-grade readiness checklist

[zaridan]

Create an infrastructure-grade readiness checklist.

Purpose:

Before Helpthread is announced as ready for external operators, evaluate it as infrastructure, not merely as an app.

Checklist areas:

• installability
• first-admin and first-mailbox onboarding
• migration safety
• configuration validation
• operational diagnostics
• mailbox health and reconnect paths
• queue/cron health
• search and retrieval
• backup, restore, export, and portability
• API and event stability
• security posture
• channel-neutral architecture
• Relay readiness
• Agent Exchange readiness
• public docs and known limitations

Acceptance:

• Checklist clearly defines what must be true before external alpha.
• Each checklist item links to existing roadmap issues where possible.
• Missing work is converted into issues rather than left as prose.
• The checklist distinguishes launch blockers from future improvements.
• The checklist avoids support-inbox and email-only framing.
• The checklist is public-safe and does not expose commercial roadmap details.