chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/chromadb/utils/messageid.py

@@ -0,0 +1,8 @@
+def int_to_bytes(int: int) -> bytes:
+    """Convert int to a 24 byte big endian byte string"""
+    return int.to_bytes(24, "big")
+
+
+def bytes_to_int(bytes: bytes) -> int:
+    """Convert a 24 byte big endian byte string to an int"""
+    return int.from_bytes(bytes, "big")