fix: translate remaining NL/FR interface gaps

Role names, audit/scenario labels, and status text were previously either
left in English or only partially translated:
- auth.json/demo.json role labels actually translated (not just labelled
  as translated): Operationsmanager/Verhuurmedewerker,
  Responsable des operations/Collaborateur de location.
- "Audit trail" -> Auditgeschiedenis/Piste d'audit (title, column header,
  and every mid-sentence occurrence across demo.json, quality.json,
  returns.json -- these embedded leaks were previously invisible to the
  whole-string identity check).
- "Open" (status) -> Openstaand, "Recent" -> Recentste,
  "Start scenario" -> Scenario starten / Demarrer le scenario.

Matching Playwright spec text updated in the same commit so the suite
never regresses through a broken intermediate state.

frontend/src/i18n/locales/nl-BE/integrations.json

@@ -31,7 +31,7 @@
     "description": "Vastgelegde automatiseringspogingen met de recentste foutevidentie.",
     "filterLabel": "Weergave",
     "filterNeedsAttention": "Vraagt aandacht",
-    "filterRecent": "Recent",
+    "filterRecent": "Recentste",
     "filterSucceeded": "Geslaagd",
     "filterAll": "Alle",
     "statusFilterLabel": "Status",
@@ -41,7 +41,7 @@
     "statusSucceeded": "Geslaagd",
     "statusFailed": "Mislukt",
     "unavailable": "Automatiseringsopdrachten zijn momenteel niet beschikbaar.",
-    "managerOnly": "Automatisering is enkel zichtbaar voor Operations Managers.",
+    "managerOnly": "Automatisering is enkel zichtbaar voor Operationsmanagers.",
     "loading": "Automatiseringsopdrachten laden…",
     "empty": "Geen automatiseringsopdrachten voor dit filter.",
     "count": "{{count}} workflowgebeurtenissen",