Refactor import statements for ResponseBase in API routers

- Updated import statements in the following files to import ResponseBase directly from models instead of models.response:
  - routers/api/v1/share/__init__.py
  - routers/api/v1/site/__init__.py
  - routers/api/v1/slave/__init__.py
  - routers/api/v1/tag/__init__.py
  - routers/api/v1/user/__init__.py
  - routers/api/v1/vas/__init__.py
  - routers/api/v1/webdav/__init__.py

Enhance user registration and related endpoints in user router

- Changed return type annotations from models.response.ResponseBase to models.ResponseBase in multiple functions.
- Updated return statements to reflect the new import structure.
- Improved documentation for clarity.

Add PhysicalFile model and storage service implementation

- Introduced PhysicalFile model to represent actual files on disk with reference counting logic.
- Created storage service module with local storage implementation, including file operations and error handling.
- Defined exceptions for storage operations to improve error handling.
- Implemented naming rule parser for generating file and directory names based on templates.

Update dependency management in uv.lock

- Added aiofiles version 25.1.0 to the project dependencies.

models/physical_file.py

@@ -0,0 +1,90 @@
+"""
+物理文件模型
+
+表示磁盘上的实际文件。多个 Object 可以引用同一个 PhysicalFile，
+实现文件共享而不复制物理文件。
+
+引用计数逻辑：
+- 每个引用此文件的 Object 都会增加引用计数
+- 当 Object 被删除时，减少引用计数
+- 只有当引用计数为 0 时，才物理删除文件
+"""
+from typing import TYPE_CHECKING
+from uuid import UUID
+
+from sqlmodel import Field, Relationship, Index
+
+from .base import SQLModelBase
+from .mixin import UUIDTableBaseMixin
+
+if TYPE_CHECKING:
+    from .object import Object
+    from .policy import Policy
+
+
+class PhysicalFileBase(SQLModelBase):
+    """物理文件基础模型"""
+
+    storage_path: str = Field(max_length=512)
+    """物理存储路径（相对于存储策略根目录）"""
+
+    size: int = 0
+    """文件大小（字节）"""
+
+    checksum_md5: str | None = Field(default=None, max_length=32)
+    """MD5校验和（用于文件去重和完整性校验）"""
+
+
+class PhysicalFile(PhysicalFileBase, UUIDTableBaseMixin):
+    """
+    物理文件模型
+
+    表示磁盘上的实际文件。多个 Object 可以引用同一个 PhysicalFile，
+    实现文件共享而不复制物理文件。
+    """
+
+    __table_args__ = (
+        Index("ix_physical_file_policy_path", "policy_id", "storage_path"),
+        Index("ix_physical_file_checksum", "checksum_md5"),
+    )
+
+    policy_id: UUID = Field(
+        foreign_key="policy.id",
+        index=True,
+        ondelete="RESTRICT",
+    )
+    """存储策略UUID"""
+
+    reference_count: int = Field(default=1, ge=0)
+    """引用计数（有多少个 Object 引用此物理文件）"""
+
+    # 关系
+    policy: "Policy" = Relationship()
+    """存储策略"""
+
+    objects: list["Object"] = Relationship(back_populates="physical_file")
+    """引用此物理文件的所有逻辑对象"""
+
+    def increment_reference(self) -> int:
+        """
+        增加引用计数
+
+        :return: 更新后的引用计数
+        """
+        self.reference_count += 1
+        return self.reference_count
+
+    def decrement_reference(self) -> int:
+        """
+        减少引用计数
+
+        :return: 更新后的引用计数
+        """
+        if self.reference_count > 0:
+            self.reference_count -= 1
+        return self.reference_count
+
+    @property
+    def can_be_deleted(self) -> bool:
+        """是否可以物理删除（引用计数为0）"""
+        return self.reference_count == 0