add local storage in json for collection

src/app/page.tsx

@@ -1,7 +1,7 @@
 "use client";
 import React, { useEffect, useMemo, useState } from 'react';
 import type { TcgCard } from '@/types/pokemon';
-import { loadChecklist, saveChecklist } from '@/lib/checklist';
+import { loadChecklistServer, saveChecklistServer } from '@/lib/checklist';
 import type { ChecklistV2, VariantKey } from '@/lib/checklist';
 import CardGrid from '@/components/CardGrid';
 import Header from '@/components/Header';
@@ -18,7 +18,10 @@ export default function Page() {
   const [tab, setTab] = useState<'uncollected' | 'collected'>('uncollected');
 
   useEffect(() => {
-    setChecklist(loadChecklist());
+    (async () => {
+      const data = await loadChecklistServer();
+      setChecklist(data);
+    })();
   }, []);
 
   useEffect(() => {
@@ -48,7 +51,8 @@ export default function Page() {
       // Clean up empty records to keep storage tidy
       const hasAny = Object.values(current).some(Boolean);
       if (hasAny) next[id] = current; else delete next[id];
-      saveChecklist(next);
+      // fire-and-forget save to server; fallback handled in lib
+      void saveChecklistServer(next);
       return next;
     });
   }