Sanitize for open-source release

- Replace internal tenant name yitanger.feishu.cn with your-tenant.feishu.cn
- Replace real wiki token with placeholder WikiNodeTokenExample
- Parameterize tenant via FEISHU_TENANT env var in feishu-to-md.mjs
- Expand .gitignore to cover cookies, auth artifacts, IDE files

feishu-copy.mjs

@@ -27,8 +27,8 @@ if (!argv[0] || argv[0] === '--help' || argv[0] === '-h') {
   目标文件夹token    可选，新文档放在指定文件夹下
 
 示例：
-  node feishu-copy.mjs https://yitanger.feishu.cn/wiki/R9NywV2i9izjuqkPd63cWuafn4g
-  node feishu-copy.mjs https://yitanger.feishu.cn/wiki/ABC123 fldcnXXXXXXX
+  node feishu-copy.mjs https://your-tenant.feishu.cn/wiki/WikiNodeTokenExample
+  node feishu-copy.mjs https://your-tenant.feishu.cn/wiki/ABC123 fldcnXXXXXXX
 `);
   process.exit(0);
 }