Standardize store exports to named useXxxStore convention

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/stores/performance.js

@@ -2,7 +2,7 @@ import { defineStore } from "pinia";
 import apiClient from "@/api/client.js";
 import apiError from '@/module/apiError.js';
 
-export default defineStore('performanceStore', {
+export const usePerformanceStore = defineStore('performanceStore', {
   state: () => ({
     allPerformanceData: null,
     freqChartData: null,