fix: exclude functions/ sub-project from the root Vitest run

vite.config.ts

@@ -15,6 +15,7 @@ export default defineConfig({
       '**/.{idea,git,cache,output,temp}/**',
       '**/{karma,rollup,webpack,vite,vitest,jest,ava,babel,nyc,cypress,tsup,build}.config.*',
       'firebase-tests/**',
+      'functions/**',
     ],
   },
 })