build: use manual chunks to reduce dist size

lib/ai/providers.ts

@@ -1,4 +1,3 @@
-import { createOpenAI } from '@ai-sdk/openai'
 import { getEncoding } from 'js-tiktoken'
 
 import { RecursiveCharacterTextSplitter } from './text-splitter'

nuxt.config.ts

@@ -9,6 +9,20 @@ export default defineNuxtConfig({
     storage: 'cookie',
   },
 
+  vite: {
+    build: {
+      rollupOptions: {
+        output: {
+          manualChunks(id) {
+            if (id.includes('js-tiktoken')) {
+              return 'tiktoken'
+            }
+          },
+        },
+      },
+    },
+  },
+
   css: ['~/assets/css/main.css'],
   compatibilityDate: '2024-11-01',
   devtools: { enabled: true },