feat(confidence-engine): use server investigation persistence

app/api/investigations/[id]/restart/route.js

@@ -0,0 +1,14 @@
+import { restartInvestigation } from "@/lib/storage/server-investigation-persistence.js";
+import { withAuthenticatedApi } from "@/lib/supabase/api-auth.js";
+
+async function post(_request, { params }) {
+  try {
+    const snapshot = await restartInvestigation(params.id);
+    if (!snapshot) return Response.json({ error: "Investigation not found" }, { status: 404 });
+    return Response.json({ snapshot });
+  } catch {
+    return Response.json({ error: "Investigation persistence request failed" }, { status: 500 });
+  }
+}
+
+export const POST = withAuthenticatedApi(post);