feat: implement snapshot restore functionality and enhance graph state management

src/components/admin/KnowledgeGraph.jsx

@@ -25,9 +25,12 @@ const KnowledgeGraph = () => {
   const [showExcludeNodes, setShowExcludeNodes] = useState(false);
   const [isAnalyzing, setIsAnalyzing] = useState(false);
   const [analyzeError, setAnalyzeError] = useState(null);
+  const [isRestoring, setIsRestoring] = useState(false);
 
-  const { topics, relations, reload, updateTopic, deleteTopic, addRelation, removeRelation, bulkSave } =
-    useGraphData();
+  const {
+    topics, relations, snapshotMeta,
+    reload, updateTopic, deleteTopic, addRelation, removeRelation, bulkSave, restoreSnapshot,
+  } = useGraphData();
 
   // ── Canvas sizing ────────────────────────────────────────────────────────────
 
@@ -177,6 +180,24 @@ const KnowledgeGraph = () => {
     }
   }, [selectedNode, deleteTopic]);
 
+  // ── Snapshot restore ─────────────────────────────────────────────────────────
+
+  const handleRestore = useCallback(async () => {
+    if (
+      !confirm(
+        `Restore the graph to the snapshot from ${new Date(snapshotMeta?.ts).toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' })}?\n\nThis will undo the last Analyze & Optimize run. The snapshot will be cleared after restoring.`,
+      )
+    )
+      return;
+    setIsRestoring(true);
+    try {
+      await restoreSnapshot();
+      setSelectedNode(null);
+    } finally {
+      setIsRestoring(false);
+    }
+  }, [restoreSnapshot, snapshotMeta]);
+
   // ── AI graph analysis ────────────────────────────────────────────────────────
 
   const analyzeGraph = useCallback(async () => {
@@ -309,6 +330,9 @@ Do not return the entire graph — only the actions to take.`;
           analyzeError={analyzeError}
           disabled={topics.length === 0}
           onApplied={reload}
+          snapshotMeta={snapshotMeta}
+          onRestore={handleRestore}
+          isRestoring={isRestoring}
         />
         <NodeDetailPanel
           selectedNode={selectedNode}