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/sources.py

@@ -0,0 +1,147 @@
+"""Save DOT code objects, render with Graphviz dot, and open in viewer."""
+
+import locale
+import logging
+import os
+import typing
+
+from .encoding import DEFAULT_ENCODING
+from . import _tools
+from . import saving
+from . import jupyter_integration
+from . import piping
+from . import rendering
+from . import unflattening
+
+__all__ = ['Source']
+
+
+log = logging.getLogger(__name__)
+
+
+class Source(rendering.Render, saving.Save,
+             jupyter_integration.JupyterIntegration, piping.Pipe,
+             unflattening.Unflatten):
+    """Verbatim DOT source code string to be rendered by Graphviz.
+
+    Args:
+        source: The verbatim DOT source code string.
+        filename: Filename for saving the source (defaults to ``'Source.gv'``).
+        directory: (Sub)directory for source saving and rendering.
+        format: Rendering output format (``'pdf'``, ``'png'``, ...).
+        engine: Layout engine used (``'dot'``, ``'neato'``, ...).
+        encoding: Encoding for saving the source.
+
+    Note:
+        All parameters except ``source`` are optional. All of them
+        can be changed under their corresponding attribute name
+        after instance creation.
+    """
+
+    @classmethod
+    @_tools.deprecate_positional_args(supported_number=1, ignore_arg='cls')
+    def from_file(cls, filename: typing.Union[os.PathLike, str],
+                  directory: typing.Union[os.PathLike, str, None] = None,
+                  format: typing.Optional[str] = None,
+                  engine: typing.Optional[str] = None,
+                  encoding: typing.Optional[str] = DEFAULT_ENCODING,
+                  renderer: typing.Optional[str] = None,
+                  formatter: typing.Optional[str] = None) -> 'Source':
+        """Return an instance with the source string read from the given file.
+
+        Args:
+            filename: Filename for loading/saving the source.
+            directory: (Sub)directory for source loading/saving and rendering.
+            format: Rendering output format (``'pdf'``, ``'png'``, ...).
+            engine: Layout command used (``'dot'``, ``'neato'``, ...).
+            encoding: Encoding for loading/saving the source.
+        """
+        directory = _tools.promote_pathlike_directory(directory)
+        filepath = (os.path.join(directory, filename) if directory.parts
+                    else os.fspath(filename))
+
+        if encoding is None:
+            encoding = locale.getpreferredencoding()
+
+        log.debug('read %r with encoding %r', filepath, encoding)
+        with open(filepath, encoding=encoding) as fd:
+            source = fd.read()
+
+        return cls(source,
+                   filename=filename, directory=directory,
+                   format=format, engine=engine, encoding=encoding,
+                   renderer=renderer, formatter=formatter,
+                   loaded_from_path=filepath)
+
+    @_tools.deprecate_positional_args(supported_number=1, ignore_arg='self')
+    def __init__(self, source: str,
+                 filename: typing.Union[os.PathLike, str, None] = None,
+                 directory: typing.Union[os.PathLike, str, None] = None,
+                 format: typing.Optional[str] = None,
+                 engine: typing.Optional[str] = None,
+                 encoding: typing.Optional[str] = DEFAULT_ENCODING, *,
+                 renderer: typing.Optional[str] = None,
+                 formatter: typing.Optional[str] = None,
+                 loaded_from_path: typing.Optional[os.PathLike] = None) -> None:
+        super().__init__(filename=filename, directory=directory,
+                         format=format, engine=engine,
+                         renderer=renderer, formatter=formatter,
+                         encoding=encoding)
+        self._loaded_from_path = loaded_from_path
+        self._source = source
+
+    # work around pytype false alarm
+    _source: str
+    _loaded_from_path: typing.Optional[os.PathLike]
+
+    def _copy_kwargs(self, **kwargs):
+        """Return the kwargs to create a copy of the instance."""
+        return super()._copy_kwargs(source=self._source,
+                                    loaded_from_path=self._loaded_from_path,
+                                    **kwargs)
+
+    def __iter__(self) -> typing.Iterator[str]:
+        r"""Yield the DOT source code read from file line by line.
+
+        Yields: Line ending with a newline (``'\n'``).
+        """
+        lines = self._source.splitlines(keepends=True)
+        yield from lines[:-1]
+        for line in lines[-1:]:
+            suffix = '\n' if not line.endswith('\n') else ''
+            yield line + suffix
+
+    @property
+    def source(self) -> str:
+        """The DOT source code as string.
+
+        Normalizes so that the string always ends in a final newline.
+        """
+        source = self._source
+        if not source.endswith('\n'):
+            source += '\n'
+        return source
+
+    @_tools.deprecate_positional_args(supported_number=1, ignore_arg='self')
+    def save(self, filename: typing.Union[os.PathLike, str, None] = None,
+             directory: typing.Union[os.PathLike, str, None] = None, *,
+             skip_existing: typing.Optional[bool] = None) -> str:
+        """Save the DOT source to file. Ensure the file ends with a newline.
+
+        Args:
+            filename: Filename for saving the source (defaults to ``name`` + ``'.gv'``)
+            directory: (Sub)directory for source saving and rendering.
+            skip_existing: Skip write if file exists (default: ``None``).
+                By default skips if instance was loaded from the target path:
+                ``.from_file(self.filepath)``.
+
+        Returns:
+            The (possibly relative) path of the saved source file.
+        """
+        skip = (skip_existing is None and self._loaded_from_path
+                and os.path.samefile(self._loaded_from_path, self.filepath))
+        if skip:
+            log.debug('.save(skip_existing=None) skip writing Source.from_file(%r)',
+                      self.filepath)
+        return super().save(filename=filename, directory=directory,
+                            skip_existing=skip)