Safe pattern for unauthenticated production-data UI previews

Candidate pattern from COR-3923 / draft PR #757: For an unauthenticated design-review preview backed by real production state, publish a bounded frozen snapshot instead of connecting the public runtime to the production database. Strip direct contacts, message and note bodies, signed URLs and attachments, credentials, and raw internal/provider/user IDs; retain only the operational fields needed to evaluate the UI. Serve the snapshot through a production-mode isolated service with a strict route allowlist, no database credentials, and read-only UI actions. Verify both sides of the boundary: intended preview/API/health routes return 200, while the app root, authenticated support pages, and real support APIs return 404. This preserved realistic queue counts, case state, and Quo direction/timestamps while preventing the preview from becoming a public production-data surface.