feat: 全量功能模块开发与集成测试修复

- 新增后端模块：Alert、APIAsset、Compliance、Lineage、Masking、Risk、SchemaChange、Unstructured、Watermark
- 新增前端模块页面与API接口
- 新增Alembic迁移脚本(002-014)覆盖全量业务表
- 新增测试数据生成脚本与集成测试脚本
- 修复metadata模型JSON类型导入缺失导致启动失败的问题
- 修复前端Alert/APIAsset页面request模块路径错误
- 更新docker-compose与开发计划文档

backend/app/models/schema_change.py

@@ -0,0 +1,23 @@
+from datetime import datetime
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey
+from sqlalchemy.orm import relationship
+from app.core.database import Base
+
+
+class SchemaChangeLog(Base):
+    __tablename__ = "schema_change_log"
+
+    id = Column(Integer, primary_key=True, index=True)
+    source_id = Column(Integer, ForeignKey("data_source.id"), nullable=False)
+    database_id = Column(Integer, ForeignKey("meta_database.id"), nullable=True)
+    table_id = Column(Integer, ForeignKey("meta_table.id"), nullable=True)
+    column_id = Column(Integer, ForeignKey("meta_column.id"), nullable=True)
+    change_type = Column(String(20), nullable=False)  # add_table, drop_table, add_column, drop_column, change_type, change_comment
+    old_value = Column(Text)
+    new_value = Column(Text)
+    detected_at = Column(DateTime, default=datetime.utcnow)
+
+    source = relationship("DataSource")
+    database = relationship("Database")
+    table = relationship("DataTable")
+    column = relationship("DataColumn")