Define the nonrotating combined-example validation case

experiments/plateau_combined_cases.json

@@ -0,0 +1,13 @@
+[
+  {
+    "id": "n1_J0_no_central_R160",
+    "arguments": [
+      "--index", "1",
+      "--angular-momentum", "0",
+      "--no-central",
+      "--restart", "160",
+      "--max-newton", "8"
+    ],
+    "notes": "Nonrotating physical counterpart of the combined sandbox example; strict Newton tolerance and q14/q18 physical validation."
+  }
+]