fix: expose same-name FK candidates from the controlled DWH stub

backend/scripts/p2-acceptance.mjs

@@ -566,7 +566,9 @@ async function startServers(ctx) {
           column,
           type: inferColumnType(first[column]),
           nullable: false,
-          pk: column === "id",
+          // `patient_id` is marked as a primary key so the same-name FK heuristic can discover
+          // joins from every table that carries it, giving the full-run FK checkpoint candidates.
+          pk: column === "id" || column === "patient_id",
           default: null,
         })));
         return;