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/pygments/lexers/math.py

@@ -0,0 +1,21 @@
+"""
+    pygments.lexers.math
+    ~~~~~~~~~~~~~~~~~~~~
+
+    Just export lexers that were contained in this module.
+
+    :copyright: Copyright 2006-2025 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+# ruff: noqa: F401
+from pygments.lexers.python import NumPyLexer
+from pygments.lexers.matlab import MatlabLexer, MatlabSessionLexer, \
+    OctaveLexer, ScilabLexer
+from pygments.lexers.julia import JuliaLexer, JuliaConsoleLexer
+from pygments.lexers.r import RConsoleLexer, SLexer, RdLexer
+from pygments.lexers.modeling import BugsLexer, JagsLexer, StanLexer
+from pygments.lexers.idl import IDLLexer
+from pygments.lexers.algebra import MuPADLexer
+
+__all__ = []