feat: add A-card operations frontend and backend foundation

frontend/app/hooks/use-persistent-state.ts

@@ -0,0 +1,24 @@
+import { type Dispatch, type SetStateAction, useEffect, useState } from "react";
+
+export function usePersistentState<T>(key: string, initialValue: T | (() => T)): [T, Dispatch<SetStateAction<T>>] {
+  const [value, setValue] = useState<T>(() => {
+    const fallback = typeof initialValue === "function" ? (initialValue as () => T)() : initialValue;
+    if (typeof window === "undefined") return fallback;
+    try {
+      const stored = window.localStorage.getItem(key);
+      return stored ? JSON.parse(stored) as T : fallback;
+    } catch {
+      return fallback;
+    }
+  });
+
+  useEffect(() => {
+    try {
+      window.localStorage.setItem(key, JSON.stringify(value));
+    } catch {
+      // Storage can be unavailable in private mode; in-memory state still works.
+    }
+  }, [key, value]);
+
+  return [value, setValue];
+}