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/flatbuffers/compat.py

@@ -0,0 +1,91 @@
+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""A tiny version of `six` to help with backwards compability.
+
+Also includes compatibility helpers for numpy.
+"""
+
+import sys
+
+PY2 = sys.version_info[0] == 2
+PY26 = sys.version_info[0:2] == (2, 6)
+PY27 = sys.version_info[0:2] == (2, 7)
+PY275 = sys.version_info[0:3] >= (2, 7, 5)
+PY3 = sys.version_info[0] == 3
+PY34 = sys.version_info[0:2] >= (3, 4)
+
+if PY3:
+  import importlib.machinery
+
+  string_types = (str,)
+  binary_types = (bytes, bytearray)
+  range_func = range
+  memoryview_type = memoryview
+  struct_bool_decl = "?"
+else:
+  import imp
+
+  string_types = (unicode,)
+  if PY26 or PY27:
+    binary_types = (str, bytearray)
+  else:
+    binary_types = (str,)
+  range_func = xrange
+  if PY26 or (PY27 and not PY275):
+    memoryview_type = buffer
+    struct_bool_decl = "<b"
+  else:
+    memoryview_type = memoryview
+    struct_bool_decl = "?"
+
+# Helper functions to facilitate making numpy optional instead of required
+
+
+def import_numpy():
+  """Returns the numpy module if it exists on the system,
+
+  otherwise returns None.
+  """
+  if PY3:
+    numpy_exists = importlib.machinery.PathFinder.find_spec("numpy") is not None
+  else:
+    try:
+      imp.find_module("numpy")
+      numpy_exists = True
+    except ImportError:
+      numpy_exists = False
+
+  if numpy_exists:
+    # We do this outside of try/except block in case numpy exists
+    # but is not installed correctly. We do not want to catch an
+    # incorrect installation which would manifest as an
+    # ImportError.
+    import numpy as np
+  else:
+    np = None
+
+  return np
+
+
+class NumpyRequiredForThisFeature(RuntimeError):
+  """Error raised when user tries to use a feature that
+
+  requires numpy without having numpy installed.
+  """
+
+  pass
+
+
+# NOTE: Future Jython support may require code here (look at `six`).