Last window's multi-tenant authority cluster finally tagged in v2026.618.0

What this changes for operators

• v2026.618.0 (June 18) is the tag that finally contains last window's master-only authority cluster: cloud-tenant instance-admin deprivileging (#7525), per-company JWT signing keys (#5864), plugin tenant isolation (#5865), the negated-phrasing review-approval fix (#5839), and HTTP-log credential redaction (#8013). Shared-pool and cloud-tenant operators must upgrade.
• Provision a separate non-cloud-tenant admin identity first: the deprivileging purges stale instance-admin rows by design.