fix: align video generation payloads

apps/api/internal/clients/simulation.go

@@ -339,5 +339,12 @@ func firstNonEmptyPrompt(body map[string]any, fallback string) string {
 			return value
 		}
 	}
+	for _, item := range contentItems(body["content"]) {
+		if stringValue(item, "type") == "text" {
+			if value := strings.TrimSpace(stringValue(item, "text")); value != "" {
+				return value
+			}
+		}
+	}
 	return fallback
 }