fix(confidence-engine): sanitize reasoning error responses

app/api/focused-investigation/deconstruct/route.js

@@ -154,7 +154,7 @@ async function post(request) {
       );
     }
     return Response.json(
-      { error: e.message || "Unknown server error" },
+      { error: "Reasoning request could not be completed." },
       { status: 500 },
     );
   }