fix(admin): persist posts grid size choice across reloads

src/app/p/[secret]/posts/page.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState } from "react";
+import { useEffect, useState } from "react";
 import { useInfiniteQuery, useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { useTRPC } from "@/trpc/client";
 import { Trash2, MessageSquare, Loader2, ChevronDown, Play, ImageOff, PawPrint } from "lucide-react";
@@ -22,11 +22,27 @@ const GRID_COLS_CLASS: Record<GridSize, string> = {
   8: "sm:grid-cols-4 lg:grid-cols-8",
 };
 
+const GRID_SIZE_STORAGE_KEY = "pawfeed-admin-posts-grid-size";
+
 export default function AdminPostsPage() {
   const trpc = useTRPC();
   const qc = useQueryClient();
   const [search, setSearch] = useState("");
   const [gridSize, setGridSize] = useState<GridSize>(3);
+
+  // Reads the persisted choice after mount (SSR has no localStorage access —
+  // same pattern as ActivePetContext, a brief default-then-update on first paint).
+  useEffect(() => {
+    const stored = Number(window.localStorage.getItem(GRID_SIZE_STORAGE_KEY));
+    if (GRID_SIZES.includes(stored as GridSize)) {
+      setGridSize(stored as GridSize);
+    }
+  }, []);
+
+  function handleGridSizeChange(size: GridSize) {
+    setGridSize(size);
+    window.localStorage.setItem(GRID_SIZE_STORAGE_KEY, String(size));
+  }
   const [commentsPostId, setCommentsPostId] = useState<string | null>(null);
   const [deleteTarget, setDeleteTarget] = useState<{ id: string; type: "post" | "comment" } | null>(null);
   const [reason, setReason] = useState("");
@@ -88,7 +104,7 @@ export default function AdminPostsPage() {
               <button
                 key={size}
                 type="button"
-                onClick={() => setGridSize(size)}
+                onClick={() => handleGridSizeChange(size)}
                 aria-pressed={gridSize === size}
                 className={cn(
                   "rounded-md px-2.5 py-1 text-xs font-medium transition-colors",