Migrate Vitest store tests from vi.mock to MSW request handlers

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

vite.config.js

@@ -89,6 +89,9 @@ export default defineConfig(({ mode }) => {
     test: {
       globals: true,
       environment: "jsdom",
+      environmentOptions: {
+        jsdom: { url: "http://localhost:3000" },
+      },
       setupFiles: ["./tests/setup-msw.js"],
       // reporter: ['text', 'json', 'html', 'vue'],
     },