Refactor document handling and update Milvus collection settings

- Removed multiple failed document entries from `documents.json`.
- Added a new document entry with updated metadata and changed the index name to `regulations_dense_1024_v2`.
- Updated architecture documentation to reflect changes in the Milvus collection name.
- Adjusted requirements by removing the sqlalchemy dependency.
- Modified test cases to align with new document structure and naming conventions.
- Introduced a new test file for Milvus vector index runtime recovery and error handling.
- Updated assertions in various test files to ensure compatibility with the new schema.

backend/app/config/settings.py

@@ -33,7 +33,7 @@ class Settings(BaseSettings):
     # Keep configuration setup explicit so runtime behavior is easy to reason about.
     milvus_host: str = Field(default="6.86.80.8", description="Milvus服务地址")
     milvus_port: int = Field(default=19530, description="Milvus服务端口")
-    milvus_collection: str = Field(default="regulations_dense_1024_v1", description="法规向量集合名称")
+    milvus_collection: str = Field(default="regulations_dense_1024_v2", description="法规向量集合名称")
     milvus_db_name: str = Field(default="default", description="Milvus数据库名称")
 
     # Keep configuration setup explicit so runtime behavior is easy to reason about.