refactor(api): 重构数据库访问为SQLAlchemy绑定的session

- 统一移除手动创建的数据库session，统一使用models模块中的db.session
- 修正项目创建接口，增加开始和结束日期的格式验证与处理
- 更新导入项目接口，使用枚举类型校验项目类型并优化异常处理
- 更新统计接口，避免多次查询假期数据，优化日期字符串处理
- 删除回滚前多余的session关闭调用，改为使用db.session.rollback()
- app.py中重构数据库初始化：统一配置SQLAlchemy，动态创建数据库路径和表
- 项目模型新增开始日期和结束日期字段支持
- 添加导入批次历史记录模型支持
- 优化工具函数中日期类型提示，移除无用导入
- 更新requirements.txt依赖版本回退，确保兼容性
- 前端菜单添加导入历史导航入口，实现页面访问路由绑定

backend/models/models.py

@@ -1,16 +1,16 @@
+from flask_sqlalchemy import SQLAlchemy
 from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text, Date, Time, ForeignKey, Enum
-from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import relationship
 from datetime import datetime
 import enum
 
-Base = declarative_base()
+db = SQLAlchemy()
 
 class ProjectType(enum.Enum):
     TRADITIONAL = "traditional"  # 传统项目
     PSI = "psi"                  # PSI项目
 
-class Project(Base):
+class Project(db.Model):
     """项目表模型"""
     __tablename__ = 'projects'
     
@@ -26,6 +26,8 @@ class Project(Base):
     contract_number = Column(String(100))  # 合同号，PSI项目必填
     
     description = Column(Text)
+    start_date = Column(Date, nullable=True) # 项目开始时间
+    end_date = Column(Date, nullable=True)  # 项目结束时间
     is_active = Column(Boolean, default=True)
     created_at = Column(DateTime, default=datetime.utcnow)
     updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
@@ -42,12 +44,14 @@ class Project(Base):
             'customer_name': self.customer_name,
             'contract_number': self.contract_number,
             'description': self.description,
+            'start_date': self.start_date.isoformat() if self.start_date else None,
+            'end_date': self.end_date.isoformat() if self.end_date else None,
             'is_active': self.is_active,
             'created_at': self.created_at.isoformat() if self.created_at else None,
             'updated_at': self.updated_at.isoformat() if self.updated_at else None
         }
 
-class TimeRecord(Base):
+class TimeRecord(db.Model):
     """工时记录表模型"""
     __tablename__ = 'time_records'
     
@@ -88,7 +92,7 @@ class TimeRecord(Base):
             'updated_at': self.updated_at.isoformat() if self.updated_at else None
         }
 
-class Holiday(Base):
+class Holiday(db.Model):
     """休息日配置表模型"""
     __tablename__ = 'holidays'
     
@@ -109,7 +113,7 @@ class Holiday(Base):
             'created_at': self.created_at.isoformat() if self.created_at else None
         }
 
-class CutoffPeriod(Base):
+class CutoffPeriod(db.Model):
     """Cut-Off周期表模型"""
     __tablename__ = 'cutoff_periods'
     
@@ -134,4 +138,29 @@ class CutoffPeriod(Base):
             'year': self.year,
             'month': self.month,
             'created_at': self.created_at.isoformat() if self.created_at else None
-        }
+        }
+
+class ImportBatch(db.Model):
+    """导入批次历史记录模型"""
+    __tablename__ = 'import_batches'
+
+    id = Column(Integer, primary_key=True)
+    import_date = Column(DateTime, default=datetime.utcnow)
+    status = Column(String(50), nullable=False)
+    success_count = Column(Integer, default=0)
+    failure_count = Column(Integer, default=0)
+    total_records = Column(Integer, default=0)
+    source_preview = Column(Text)
+    failures_log = Column(Text) # 存储失败记录的详细日志
+
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'import_date': self.import_date.isoformat(),
+            'status': self.status,
+            'success_count': self.success_count,
+            'failure_count': self.failure_count,
+            'total_records': self.total_records,
+            'source_preview': self.source_preview,
+            'failures_log': self.failures_log
+        }