issue 4531 slice 32: PublishingShell runtime chrome uses the message catalog #4837

Parent: #4531

Slice goal

Runtime section labels that are still raw English (Site, Publish server, Refresh, Idle, Demand publish, Content ids, Queue demand, Clear site record, Purge log, and similar) resolve through the publishing message catalog, including the default en-us TMX entries.

Out of scope

New runtime actions, full locale packs, job-detail chrome (slice 29 already shipped).

Acceptance

• Runtime section renders catalog strings; a unit test or Playwright assertion checks a key rather than a hardcoded English-only node when the catalog is loaded.
• One locale (en-us) only — do not backfill pl/sv/tr.
• product-docs only if operator-visible behavior changes; otherwise a one-line N/A is acceptable if this is string-catalog only with identical behavior. Prefer a short admin note if labels operators see are newly documented.
• Update parent [8.2] Unified publishing — next React increments #4531 Agent progress.