清理重复的 Vitest configuration file

Deleted vitest.config.ts, which contained test environment and path alias settings. This may indicate a change in testing strategy or migration away from Vitest.

vitest.config.ts

@@ -1,15 +0,0 @@
-import { defineConfig } from 'vitest/config';
-import { resolve } from 'path';
-
-export default defineConfig({
-  test: {
-    environment: 'node',
-    globals: true,
-    include: ['packages/napcat-test/**/*.test.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
-  },
-  resolve: {
-    alias: {
-      '@': resolve(__dirname, 'packages'),
-    },
-  },
-});