refine(confidence-engine): clarify portfolio investigation actions

app/page.jsx

@@ -1,7 +1,7 @@
 "use client";
 
 import React from "react";
-import { loadInvestigation } from "@/lib/storage/investigation-storage";
+import { loadInvestigation, clearInvestigation } from "@/lib/storage/investigation-storage";
 import Link from "next/link";
 
 const INVESTIGATION_ID = "case-1";
@@ -50,15 +50,17 @@ function Portfolio() {
                 href={`/investigations/${INVESTIGATION_ID}`}
                 className="rounded-lg border border-teal-600 bg-white px-4 py-2 font-medium text-teal-700 hover:bg-teal-50 transition"
               >
-                Open investigation
+                Continue investigation
               </Link>
 
-              <Link
-                href={`/investigations/${INVESTIGATION_ID}`}
-                className="rounded-lg border border-teal-600 bg-white px-4 py-2 font-medium text-teal-700 hover:bg-teal-50 transition"
+              <button
+                onClick={() => {
+                  try { clearInvestigation(); } catch (_) { /* storage must not crash caller */ }
+                }}
+                className="rounded-lg border border-red-400 bg-white px-4 py-2 font-medium text-red-700 hover:bg-red-50 transition"
               >
-                Create new investigation
-              </Link>
+                Restart investigation
+              </button>
             </div>
           </div>
         </section>