Add boilerplate files and licenses

src/hooks/usePersistedState.ts

@@ -0,0 +1,27 @@
+import { useState } from 'preact/hooks';
+
+function usePersistedState<T>(key: string, defaultValue: T): [T, (value: T) => void] {
+  const [state, setState] = useState<T>(() => {
+    try {
+      const item = localStorage.getItem(key);
+      return item ? JSON.parse(item) : defaultValue;
+    } catch (error) {
+      console.warn(`Error reading localStorage key "${key}":`, error);
+      return defaultValue;
+    }
+  });
+
+  const setPersistedState = (value: T) => {
+    try {
+      setState(value);
+      localStorage.setItem(key, JSON.stringify(value));
+    } catch (error) {
+      console.warn(`Error writing to localStorage key "${key}":`, error);
+      setState(value);
+    }
+  };
+
+  return [state, setPersistedState];
+}
+
+export default usePersistedState;