feat(backend): 更新核心模块和文件处理

- 更新配置模块 (config.py)
- 更新数据库连接 (database.py)
- 更新主应用入口 (main.py)
- 更新数据模型 (models.py)
- 更新基础 Schema (base.py)
- 更新文件处理器 (docx, excel, pdf)
- 更新 Dockerfile

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/models/models.py

@@ -51,7 +51,7 @@ class Chunk(Base, UUIDMixin, TimestampMixin):
     content = Column(Text, nullable=False)
     summary = Column(Text)
     word_count = Column(Integer)
-    metadata = Column(JSON)  # store additional info like headings, page numbers
+    extra_data = Column(JSON)  # store additional info like headings, page numbers
 
     # Relationships
     project = relationship("Project", back_populates="chunks")
@@ -112,7 +112,7 @@ class Dataset(Base, UUIDMixin, TimestampMixin):
     name = Column(String(255), nullable=False)
     description = Column(Text)
     dataset_type = Column(String(50))  # qa, conversation, instruction
-    metadata = Column(JSON)
+    extra_data = Column(JSON)
 
     # Relationships
     project = relationship("Project", back_populates="datasets")
@@ -125,7 +125,7 @@ class EvalDataset(Base, UUIDMixin, TimestampMixin):
     project_id = Column(UUID(as_uuid=True), ForeignKey("projects.id", ondelete="CASCADE"), nullable=False)
     name = Column(String(255), nullable=False)
     question_type = Column(String(50))  # mixed, fact, reasoning
-    metadata = Column(JSON)
+    extra_data = Column(JSON)
 
     # Relationships
     project = relationship("Project", back_populates="eval_datasets")