Azure Ephemeral PR-Preview VMs — Deferred Design
Deferred design for ephemeral Azure PR-preview VMs with a cap-of-3 hard-fail policy, deployment-stacks lifecycle, drift sweeper, and composite RBAC. NOT active infrastructure — the implementation work was cut from ADR-024 (2026-05-14) on the grounds that (a) Hetzner already runs PR previews and (b) no concrete trigger demands the move. This document preserves the design so it can be lifted into an active ADR when a trigger materialises (Hetzner OOM pattern, partner with concurrent-review load, regulatory data-residency requirement, etc.). Lives in docs/infrastructure/ alongside operational infra docs but is distinguishable by the `-design` filename suffix and `status: deferred` frontmatter.