feat: remove browser build; fix build errors

package.json

@@ -10,7 +10,6 @@
   "types": "./build/index.d.ts",
   "exports": {
     ".": {
-      "browser": "./build/browser/index.js",
       "import": "./build/index.js",
       "types": "./build/index.d.ts",
       "default": "./build/index.js"

src/openai-auth.ts

-import fs from 'node:fs'
-import os from 'node:os'
+import * as fs from 'node:fs'
+import * as os from 'node:os'
 
 import delay from 'delay'
 import {

tsup.config.ts

@@ -11,20 +11,6 @@ export default defineConfig([
     sourcemap: true,
     minify: false,
     shims: true,
-    dts: true,
-    external: ['undici']
-  },
-  {
-    entry: ['src/index.ts'],
-    outDir: 'build/browser',
-    target: 'chrome89',
-    platform: 'browser',
-    format: ['esm'],
-    splitting: false,
-    sourcemap: true,
-    minify: false,
-    shims: true,
-    dts: true,
-    external: ['undici']
+    dts: true
   }
 ])