[Story]: 99.9% uptime SLA definition and public status page

## Summary
Define and publish a formal SLA: 99.9% minimum uptime commitment, a defined penalty/credit schedule, and a public status page reflecting real measured uptime.

## Intent / Source of truth
99.9% uptime with defined penalties is the named enterprise procurement bar; a shared ticket queue and no formal commitment is insufficient at 10k seats. Part of [Epic] Formal SLA and tiered support programme.

## Scope
- [ ] SLA document: uptime definition (what counts as downtime), measurement methodology, penalty/credit schedule
- [ ] Public status page reflecting actual measured uptime (not a manually-updated page)
- [ ] Incident-communication process tied to the SLA

## Out of scope
- Infrastructure changes required to actually hit 99.9% if current uptime doesn't already support it (that's a prerequisite finding, tracked separately if the gap analysis surfaces one)

## Verification
Status page live and auto-updated from real monitoring data; SLA document reviewed by whoever handles commercial/legal terms.

## Risk assessment
Publishing an SLA the current infrastructure can't actually meet is a commercial and legal liability — verify current measured uptime against the 99.9% bar before publishing, not after.

## AI Usage Declaration
Drafted with AI assistance during the 2026-08-13 cross-repo backlog consolidation and enterprise-readiness research. A human owns intent, verification and consequences.