refactor: clarify investigation map as ux placeholder

components/investigation-map.jsx

@@ -82,12 +82,12 @@ export default function InvestigationMap({ turnCount = 0 }) {
   if (!hasActiveTopics && groups.established.length === 0) return null;
 
   return (
-    <div className="rounded-lg border border-gray-200 bg-white p-5" role="region" aria-label="Investigation map">
+    <div className="rounded-lg border border-gray-200 bg-white p-5" role="region" aria-label="Investigation map preview">
       <h2 className="mb-1 text-sm font-semibold uppercase tracking-wide text-gray-500">
-        Investigation Map
+        Investigation Map Preview
       </h2>
       <p className="mb-3 text-xs text-gray-400">
-        We are building an understanding of your situation one question at a time.
+        This preview shows where a future reasoning map may appear. Its final shape will emerge from the reasoning engine.
       </p>
 
       <div className="space-y-px border-t border-gray-100 pt-3" role="list" aria-label="Investigation topics">