add pinia

frontend/src/stores/testStore.ts

@@ -0,0 +1,19 @@
+import { defineStore } from 'pinia';
+
+export const useCounterStore = defineStore('counter', {
+  state: () => ({
+    counter: 0
+  }),
+
+  getters: {
+    doubleCount (state) {
+      return state.counter * 2;
+    }
+  },
+
+  actions: {
+    increment () {
+      this.counter++;
+    }
+  }
+});