feat(ldap): support webdav, ftp and sftp login

[KirCute]

Description / 描述

支持 WebDAV、FTP 和 SFTP 端口使用 LDAP 验证。

用户表新增列allow_ldap，只有启用时才支持该用户通过 LDAP 登录，从旧版本升级上来后默认值为true。

Motivation and Context / 背景

How Has This Been Tested? / 测试

Checklist / 检查清单

• I have read the CONTRIBUTING document.
  我已阅读 CONTRIBUTING 文档。
• I have formatted my code with go fmt or prettier.
  我已使用 go fmt 或 prettier 格式化提交的代码。
• I have added appropriate labels to this PR (or mentioned needed labels in the description if lacking permissions).
  我已为此 PR 添加了适当的标签（如无权限或需要的标签不存在，请在描述中说明，管理员将后续处理）。
• I have requested review from relevant code authors using the "Request review" feature when applicable.
  我已在适当情况下使用"Request review"功能请求相关代码作者进行审查。
• I have updated the repository accordingly (If it’s needed).
  我已相应更新了相关仓库（若适用）。
  • OpenList-Frontend feat(ldap): support webdav, ftp and sftp login OpenList-Frontend#299
  • OpenList-Docs

[jyxjjj]

其实也没有那么Breaking。。。

[KirCute]

其实也没有那么Breaking。。。

你说得对，主要是一开始我没把allow ldap的默认值设为true，感觉有默认值以后就不breaking了

[Copilot]

Pull request overview

This PR adds support for LDAP authentication across WebDAV, FTP, and SFTP protocols. The implementation refactors LDAP login logic into a common package and introduces a new allow_ldap user field to control LDAP access per user.

Key Changes:

• Extracted LDAP authentication logic into server/common/ldap.go for reuse across multiple protocols
• Added allow_ldap boolean field to the User model with a default value of true
• Integrated LDAP authentication fallback in WebDAV, FTP, and SFTP authentication handlers

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
server/common/ldap.go	New file containing extracted LDAP authentication logic (HandleLdapLogin, LdapRegister) and dial helper function
server/handles/ldap_login.go	Refactored to use common LDAP functions; added allow_ldap permission check
server/webdav.go	Introduced tryLogin helper that attempts LDAP auth if local password validation fails and user has LDAP enabled
server/ftp.go	Added LDAP authentication fallback when password hash validation fails
server/sftp.go	Added LDAP authentication fallback when password hash validation fails
internal/model/user.go	Added AllowLdap field with default value true to control per-user LDAP access

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[KirCute]

Copilot 说有问题的代码全部是我从server/handles/ldap_login.go直接挪过去的，，，

[jyxjjj]

我觉得有几个还说的挺对的，比如连接没关我好像也没找到哪里关，另外比如那个cert verify也不应该直接去掉，应该改成驱动配置选项用户自己选。