feat: implement WebDAV protocol support with WsgiDAV + account management API

Add complete WebDAV support: management REST API (CRUD accounts at /api/v1/webdav/accounts)
and DAV protocol endpoint (/dav) using WsgiDAV + a2wsgi bridge for client access via
HTTP Basic Auth. Includes Redis+TTLCache auth caching and integration tests (24 cases).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sqlmodels/webdav.py

@@ -1,4 +1,9 @@
+"""
+WebDAV 账户模型
 
+管理用户的 WebDAV 连接账户，每个账户对应一个挂载根路径。
+通过 HTTP Basic Auth 认证访问 DAV 协议端点。
+"""
 from typing import TYPE_CHECKING
 from uuid import UUID
 
@@ -9,24 +14,104 @@ from sqlmodel_ext import SQLModelBase, TableBaseMixin
 if TYPE_CHECKING:
     from .user import User
 
-class WebDAV(SQLModelBase, TableBaseMixin):
-    """WebDAV账户模型"""
+
+# ==================== Base 模型 ====================
+
+class WebDAVBase(SQLModelBase):
+    """WebDAV 账户基础字段"""
+
+    name: str = Field(max_length=255)
+    """账户名称（同一用户下唯一）"""
+
+    root: str = Field(default="/", sa_column_kwargs={"server_default": "'/'"})
+    """挂载根目录路径"""
+
+    readonly: bool = Field(default=False, sa_column_kwargs={"server_default": "false"})
+    """是否只读"""
+
+    use_proxy: bool = Field(default=False, sa_column_kwargs={"server_default": "false"})
+    """是否使用代理下载"""
+
+
+# ==================== 数据库模型 ====================
+
+class WebDAV(WebDAVBase, TableBaseMixin):
+    """WebDAV 账户模型"""
 
     __table_args__ = (UniqueConstraint("name", "user_id", name="uq_webdav_name_user"),)
 
-    name: str = Field(max_length=255, description="WebDAV账户名")
-    password: str = Field(max_length=255, description="WebDAV密码")
-    root: str = Field(default="/", sa_column_kwargs={"server_default": "'/'"}, description="根目录路径")
-    readonly: bool = Field(default=False, description="是否只读")
-    use_proxy: bool = Field(default=False, description="是否使用代理下载")
-    
+    password: str = Field(max_length=255)
+    """密码（Argon2 哈希）"""
+
     # 外键
     user_id: UUID = Field(
         foreign_key="user.id",
         index=True,
-        ondelete="CASCADE"
+        ondelete="CASCADE",
     )
     """所属用户UUID"""
-    
+
     # 关系
-    user: "User" = Relationship(back_populates="webdavs")
+    user: "User" = Relationship(back_populates="webdavs")
+
+
+# ==================== DTO 模型 ====================
+
+class WebDAVCreateRequest(SQLModelBase):
+    """创建 WebDAV 账户请求"""
+
+    name: str = Field(max_length=255)
+    """账户名称"""
+
+    password: str = Field(min_length=1, max_length=255)
+    """账户密码（明文，服务端哈希后存储）"""
+
+    root: str = "/"
+    """挂载根目录路径"""
+
+    readonly: bool = False
+    """是否只读"""
+
+    use_proxy: bool = False
+    """是否使用代理下载"""
+
+
+class WebDAVUpdateRequest(SQLModelBase):
+    """更新 WebDAV 账户请求"""
+
+    password: str | None = Field(default=None, min_length=1, max_length=255)
+    """新密码（为 None 时不修改）"""
+
+    root: str | None = None
+    """新挂载根目录路径（为 None 时不修改）"""
+
+    readonly: bool | None = None
+    """是否只读（为 None 时不修改）"""
+
+    use_proxy: bool | None = None
+    """是否使用代理下载（为 None 时不修改）"""
+
+
+class WebDAVAccountResponse(SQLModelBase):
+    """WebDAV 账户响应"""
+
+    id: int
+    """账户ID"""
+
+    name: str
+    """账户名称"""
+
+    root: str
+    """挂载根目录路径"""
+
+    readonly: bool
+    """是否只读"""
+
+    use_proxy: bool
+    """是否使用代理下载"""
+
+    created_at: str
+    """创建时间"""
+
+    updated_at: str
+    """更新时间"""