feat: add models for physical files, policies, and user management

- Implement PhysicalFile model to manage physical file references and reference counting.
- Create Policy model with associated options and group links for storage policies.
- Introduce Redeem and Report models for handling redeem codes and reports.
- Add Settings model for site configuration and user settings management.
- Develop Share model for sharing objects with unique codes and associated metadata.
- Implement SourceLink model for managing download links associated with objects.
- Create StoragePack model for managing user storage packages.
- Add Tag model for user-defined tags with manual and automatic types.
- Implement Task model for managing background tasks with status tracking.
- Develop User model with comprehensive user management features including authentication.
- Introduce UserAuthn model for managing WebAuthn credentials.
- Create WebDAV model for managing WebDAV accounts associated with users.

sqlmodels/tag.py

@@ -0,0 +1,50 @@
+from enum import StrEnum
+from typing import TYPE_CHECKING
+from uuid import UUID
+from datetime import datetime
+
+from sqlmodel import Field, Relationship, UniqueConstraint, Column, func, DateTime
+
+from .base import SQLModelBase
+from .mixin import TableBaseMixin
+
+if TYPE_CHECKING:
+    from .user import User
+
+
+class TagType(StrEnum):
+    """标签类型枚举"""
+    MANUAL = "manual"
+    """手动标签"""
+    AUTOMATIC = "automatic"
+    """自动标签"""
+
+
+class Tag(SQLModelBase, TableBaseMixin):
+    """标签模型"""
+
+    __table_args__ = (UniqueConstraint("name", "user_id", name="uq_tag_name_user"),)
+
+    name: str = Field(max_length=255)
+    """标签名称"""
+
+    icon: str | None = Field(default=None, max_length=255)
+    """标签图标"""
+
+    color: str | None = Field(default=None, max_length=255)
+    """标签颜色"""
+
+    type: TagType = Field(default=TagType.MANUAL)
+    """标签类型"""
+    expression: str | None = Field(default=None, description="自动标签的匹配表达式")
+    
+    # 外键
+    user_id: UUID = Field(
+        foreign_key="user.id",
+        index=True,
+        ondelete="CASCADE"
+    )
+    """所属用户UUID"""
+    
+    # 关系
+    user: "User" = Relationship(back_populates="tags")