fix(build): 恢复 build-portable 的 dirname 导入，修复 Windows 便携版打包失败

scripts/build-portable.mjs

@@ -1,7 +1,7 @@
 import { cpSync, existsSync, mkdirSync, rmSync, statSync, writeFileSync, renameSync } from "node:fs"
 import { readFile } from "node:fs/promises"
 import { execSync } from "node:child_process"
-import { resolve } from "node:path"
+import { dirname, resolve } from "node:path"
 import { fileURLToPath } from "node:url"
 
 const root = resolve(dirname(fileURLToPath(import.meta.url)), "..")