chore(client): rename vitest config to .mts (ESM)

apps/client/vitest.config.ts

@@ -1,20 +0,0 @@
-/// <reference types="vitest" />
-import { defineConfig } from "vitest/config";
-import react from "@vitejs/plugin-react";
-import * as path from "path";
-
-export default defineConfig({
-  plugins: [react()],
-  resolve: {
-    alias: {
-      "@": path.resolve(__dirname, "./src"),
-    },
-  },
-  test: {
-    environment: "jsdom",
-    globals: true,
-    setupFiles: ["./src/test-setup.ts"],
-    include: ["src/**/__tests__/**/*.test.{ts,tsx}"],
-    css: false,
-  },
-});