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/multipart/__init__.py

@@ -0,0 +1,24 @@
+# This only works if using a file system, other loaders not implemented.
+
+import importlib.util
+import sys
+import warnings
+from pathlib import Path
+
+for p in sys.path:
+    file_path = Path(p, "multipart.py")
+    try:
+        if file_path.is_file():
+            spec = importlib.util.spec_from_file_location("multipart", file_path)
+            assert spec is not None, f"{file_path} found but not loadable!"
+            module = importlib.util.module_from_spec(spec)
+            sys.modules["multipart"] = module
+            assert spec.loader is not None, f"{file_path} must be loadable!"
+            spec.loader.exec_module(module)
+            break
+    except PermissionError:
+        pass
+else:
+    warnings.warn("Please use `import python_multipart` instead.", PendingDeprecationWarning, stacklevel=2)
+    from python_multipart import *
+    from python_multipart import __all__, __author__, __copyright__, __license__, __version__

backend_service/venv/lib/python3.13/site-packages/multipart/decoders.py

@@ -0,0 +1 @@
+from python_multipart.decoders import *

backend_service/venv/lib/python3.13/site-packages/multipart/exceptions.py

@@ -0,0 +1 @@
+from python_multipart.exceptions import *

backend_service/venv/lib/python3.13/site-packages/multipart/multipart.py

@@ -0,0 +1 @@
+from python_multipart.multipart import *