feat(confidence-engine): use server investigation persistence

lib/storage/providers/local-storage.js

@@ -4,6 +4,8 @@ const CANONICAL_KEY  = "confidence-engine-investigation";
 const LEGACY_KEY     = "confidence-engine-session";
 const SCHEMA_VERSION = 1;
 
+import { restartSnapshot } from "../restart-investigation.js";
+
 // Multi-Investigation key prefix (v0.60c)
 const INVESTIGATION_PREFIX = "confidence-engine-investigation:";
 
@@ -196,17 +198,7 @@ export function restartInvestigation(id) {
     const record = JSON.parse(raw);
     if (!isPlainObject(record)) return;
 
-    // Preserve container fields, reset reasoning-state fields
-    record.situationGraph = null;
-    record.selectedQuestion = null;
-    record.summary = null;
-    record.focusedContributions = [];
-    record.findings = [];
-    record.investigationReport = null;
-    record.investigationRevision = 0;
-    record.updatedAt = new Date().toISOString();
-
-    _persist(storage, key, JSON.stringify(record));
+    _persist(storage, key, JSON.stringify(restartSnapshot(record)));
   } catch (_) { /* storage errors must not crash caller */ }
 }