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/graphviz/backend/execute.py

@@ -0,0 +1,132 @@
+"""Run subprocesses with ``subprocess.run()`` and ``subprocess.Popen()``."""
+
+import errno
+import logging
+import os
+import subprocess
+import sys
+import typing
+
+from .. import _compat
+
+__all__ = ['run_check', 'ExecutableNotFound', 'CalledProcessError']
+
+
+log = logging.getLogger(__name__)
+
+
+BytesOrStrIterator = typing.Union[typing.Iterator[bytes],
+                                  typing.Iterator[str]]
+
+
+@typing.overload
+def run_check(cmd: typing.Sequence[typing.Union[os.PathLike, str]], *,
+              input_lines: typing.Optional[typing.Iterator[bytes]] = ...,
+              encoding: None = ...,
+              quiet: bool = ...,
+              **kwargs) -> subprocess.CompletedProcess:
+    """Accept bytes input_lines with default ``encoding=None```."""
+
+
+@typing.overload
+def run_check(cmd: typing.Sequence[typing.Union[os.PathLike, str]], *,
+              input_lines: typing.Optional[typing.Iterator[str]] = ...,
+              encoding: str,
+              quiet: bool = ...,
+              **kwargs) -> subprocess.CompletedProcess:
+    """Accept string input_lines when given ``encoding``."""
+
+
+@typing.overload
+def run_check(cmd: typing.Sequence[typing.Union[os.PathLike, str]], *,
+              input_lines: typing.Optional[BytesOrStrIterator] = ...,
+              encoding: typing.Optional[str] = ...,
+              capture_output: bool = ...,
+              quiet: bool = ...,
+              **kwargs) -> subprocess.CompletedProcess:
+    """Accept bytes or string input_lines depending on ``encoding``."""
+
+
+def run_check(cmd: typing.Sequence[typing.Union[os.PathLike, str]], *,
+              input_lines: typing.Optional[BytesOrStrIterator] = None,
+              encoding: typing.Optional[str] = None,
+              quiet: bool = False,
+              **kwargs) -> subprocess.CompletedProcess:
+    """Run the command described by ``cmd``
+        with ``check=True`` and return its completed process.
+
+    Raises:
+        CalledProcessError: if the returncode of the subprocess is non-zero.
+    """
+    log.debug('run %r', cmd)
+    if not kwargs.pop('check', True):  # pragma: no cover
+        raise NotImplementedError('check must be True or omited')
+
+    if encoding is not None:
+        kwargs['encoding'] = encoding
+
+    kwargs.setdefault('startupinfo', _compat.get_startupinfo())
+
+    try:
+        if input_lines is not None:
+            assert kwargs.get('input') is None
+            assert iter(input_lines) is input_lines
+            if kwargs.pop('capture_output'):
+                kwargs['stdout'] = kwargs['stderr'] = subprocess.PIPE
+            proc = _run_input_lines(cmd, input_lines, kwargs=kwargs)
+        else:
+            proc = subprocess.run(cmd, **kwargs)
+    except OSError as e:
+        if e.errno == errno.ENOENT:
+            raise ExecutableNotFound(cmd) from e
+        raise
+
+    if not quiet and proc.stderr:
+        _write_stderr(proc.stderr)
+
+    try:
+        proc.check_returncode()
+    except subprocess.CalledProcessError as e:
+        raise CalledProcessError(*e.args)
+
+    return proc
+
+
+def _run_input_lines(cmd, input_lines, *, kwargs):
+    popen = subprocess.Popen(cmd, stdin=subprocess.PIPE, **kwargs)
+
+    stdin_write = popen.stdin.write
+    for line in input_lines:
+        stdin_write(line)
+
+    stdout, stderr = popen.communicate()
+    return subprocess.CompletedProcess(popen.args, popen.returncode,
+                                       stdout=stdout, stderr=stderr)
+
+
+def _write_stderr(stderr) -> None:
+    if isinstance(stderr, bytes):
+        stderr_encoding = (getattr(sys.stderr, 'encoding', None)
+                           or sys.getdefaultencoding())
+        stderr = stderr.decode(stderr_encoding)
+
+    sys.stderr.write(stderr)
+    sys.stderr.flush()
+    return None
+
+
+class ExecutableNotFound(RuntimeError):
+    """:exc:`RuntimeError` raised if the Graphviz executable is not found."""
+
+    _msg = ('failed to execute {!r}, '
+            'make sure the Graphviz executables are on your systems\' PATH')
+
+    def __init__(self, args) -> None:
+        super().__init__(self._msg.format(*args))
+
+
+class CalledProcessError(subprocess.CalledProcessError):
+    """:exc:`~subprocess.CalledProcessError` raised if a subprocess ``returncode`` is not ``0``."""  # noqa: E501
+
+    def __str__(self) -> 'str':
+        return f'{super().__str__()} [stderr: {self.stderr!r}]'