fix: add limitedDocuments dependency to activeVersionChain useMemo

Prevents stale version chain data when documents change but the
selected node stays the same. The chainIndex ref is rebuilt in a
useEffect when limitedDocuments changes, but without this dependency
the useMemo would return cached (stale) chain data.

packages/memory-graph/src/components/memory-graph.tsx

@@ -497,7 +497,7 @@ export function MemoryGraph({
 	const activeVersionChain = useMemo(() => {
 		if (!activeNodeData || activeNodeData.type !== "memory") return null
 		return chainIndex.current.getChain(activeNodeData.id)
-	}, [activeNodeData])
+	}, [activeNodeData, limitedDocuments])
 
 	const isLoading = externalIsLoading