fix: 修复 ai 模块中 Python 脚本路径问题

使用 PROJECT_ROOT 替代 __dirname 计算，确保打包后能正确找到 tools 文件夹

api/modules/ai/routes.ts

@@ -1,16 +1,13 @@
 import express, { type Request, type Response } from 'express'
 import { spawn } from 'child_process'
 import path from 'path'
-import { fileURLToPath } from 'url'
 import fs from 'fs/promises'
 import fsSync from 'fs'
 import { asyncHandler } from '../../utils/asyncHandler.js'
 import { successResponse } from '../../utils/response.js'
 import { resolveNotebookPath } from '../../utils/pathSafety.js'
 import { ValidationError, NotFoundError, InternalError } from '../../../shared/errors/index.js'
-
-const __filename = fileURLToPath(import.meta.url)
-const __dirname = path.dirname(__filename)
+import { PROJECT_ROOT } from '../../config/paths.js'
 
 const router = express.Router()
 
@@ -89,8 +86,7 @@ router.post(
 
     const content = await fs.readFile(fullPath, 'utf-8')
 
-    const projectRoot = path.resolve(__dirname, '..', '..', '..')
-    const scriptPath = path.join(projectRoot, 'tools', 'doubao', 'main.py')
+    const scriptPath = path.join(PROJECT_ROOT, 'tools', 'doubao', 'main.py')
 
     if (!fsSync.existsSync(scriptPath)) {
       throw new InternalError(`Python script not found: ${scriptPath}`)