feat(api): expose GIAS establishment status on school payloads

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app.py

@@ -604,6 +604,7 @@ async def get_school_details(request: Request, urn: int):
             "religious_denomination": latest.get("religious_denomination", ""),
             "age_range": latest.get("age_range", ""),
             "has_sixth_form": latest.get("has_sixth_form"),
+            "status": latest.get("status"),
             "latitude": latest.get("latitude"),
             "longitude": latest.get("longitude"),
             "phase": latest.get("phase"),