feat: 完善前后端核心功能模块

后端:
- 新增认证(auth)、任务(tasks)、映射(mappings)、对账(reconciliation)、异常(exceptions)、导出(exports) API
- 新增核心模块: database, security, permissions, tenant, exceptions, error_handlers
- 新增数据模型: user, company, reconciliation_task, field_mapping, uploaded_file 等
- 新增服务层: ai_recognizer, file_parser, file_storage, mapping, reconciliation 等
- 添加数据库迁移脚本

前端:
- 新增登录页面和仪表盘页面
- 新增任务列表、任务详情、字段映射页面
- 新增异常处理页面和规则设置页面
- 新增 API 代理路由 /api/[...path]
- 新增 UI 组件库 (button, card, dialog, input, table 等)
- 新增 auth 组件 (ProtectedRoute, PermissionGate)
- 新增 layout 组件 (Header, Sidebar)
- 新增 mapping 组件 (FieldMappingTable, AISuggestionPanel)
- 新增 API 客户端和 hooks (useAsync, useToast, usePermission 等)
- 新增状态管理 (auth-store, company-store, ui-store)
- 集成 Tailwind CSS 和 shadcn/ui 组件库

其他:
- 添加 Alembic 数据库迁移配置
- 添加初始化示例数据脚本
- 更新项目文档

backend/app/models/uploaded_file.py

@@ -0,0 +1,59 @@
+from enum import Enum
+from typing import List
+
+from sqlalchemy import ForeignKey, Integer, String, BigInteger, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import BaseModel
+
+
+class FileType(str, Enum):
+    """文件类型"""
+    SALARY = "工资表"
+    SOCIAL_SECURITY = "社保表"
+    TAX = "个税表"
+
+
+class ParseStatus(str, Enum):
+    """解析状态"""
+    PENDING = "待解析"
+    PARSING = "解析中"
+    SUCCESS = "解析成功"
+    FAILED = "解析失败"
+
+
+class UploadedFile(BaseModel):
+    """
+    上传文件模型
+    
+    Attributes:
+        company_id: 企业ID
+        task_id: 对账任务ID（可选）
+        file_type: 文件类型
+        original_filename: 原始文件名
+        stored_filename: 存储文件名
+        file_size: 文件大小（字节）
+        mime_type: MIME类型
+        parse_status: 解析状态
+        parse_error: 解析错误信息
+    """
+    
+    __tablename__ = "uploaded_files"
+
+    company_id: Mapped[int] = mapped_column(Integer, ForeignKey("companies.id"), nullable=False, index=True)
+    task_id: Mapped[int | None] = mapped_column(Integer, nullable=True, index=True)
+    file_type: Mapped[str] = mapped_column(String(50), nullable=False, index=True)
+    original_filename: Mapped[str] = mapped_column(String(255), nullable=False)
+    stored_filename: Mapped[str] = mapped_column(String(255), nullable=False, unique=True)
+    file_size: Mapped[int] = mapped_column(BigInteger, nullable=False)
+    mime_type: Mapped[str] = mapped_column(String(100), nullable=False)
+    parse_status: Mapped[str] = mapped_column(String(20), nullable=False, default=ParseStatus.PENDING.value, index=True)
+    parse_error: Mapped[str | None] = mapped_column(Text, nullable=True)
+
+    # 关系
+    field_mappings: Mapped[List["FieldMapping"]] = relationship(
+        "FieldMapping", back_populates="file", lazy="selectin"
+    )
+
+    def __repr__(self) -> str:
+        return f"<UploadedFile(id={self.id}, filename='{self.original_filename}', type='{self.file_type}')>"