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/sympy/matrices/kind.py

@@ -0,0 +1,97 @@
+# sympy.matrices.kind
+
+from sympy.core.kind import Kind, _NumberKind, NumberKind
+from sympy.core.mul import Mul
+
+
+class MatrixKind(Kind):
+    """
+    Kind for all matrices in SymPy.
+
+    Basic class for this kind is ``MatrixBase`` and ``MatrixExpr``,
+    but any expression representing the matrix can have this.
+
+    Parameters
+    ==========
+
+    element_kind : Kind
+        Kind of the element. Default is
+        :class:`sympy.core.kind.NumberKind`,
+        which means that the matrix contains only numbers.
+
+    Examples
+    ========
+
+    Any instance of matrix class has kind ``MatrixKind``:
+
+    >>> from sympy import MatrixSymbol
+    >>> A = MatrixSymbol('A', 2, 2)
+    >>> A.kind
+    MatrixKind(NumberKind)
+
+    An expression representing a matrix may not be an instance of
+    the Matrix class, but it will have kind ``MatrixKind``:
+
+    >>> from sympy import MatrixExpr, Integral
+    >>> from sympy.abc import x
+    >>> intM = Integral(A, x)
+    >>> isinstance(intM, MatrixExpr)
+    False
+    >>> intM.kind
+    MatrixKind(NumberKind)
+
+    Use ``isinstance()`` to check for ``MatrixKind`` without specifying the
+    element kind. Use ``is`` to check the kind including the element kind:
+
+    >>> from sympy import Matrix
+    >>> from sympy.core import NumberKind
+    >>> from sympy.matrices import MatrixKind
+    >>> M = Matrix([1, 2])
+    >>> isinstance(M.kind, MatrixKind)
+    True
+    >>> M.kind is MatrixKind(NumberKind)
+    True
+
+    See Also
+    ========
+
+    sympy.core.kind.NumberKind
+    sympy.core.kind.UndefinedKind
+    sympy.core.containers.TupleKind
+    sympy.sets.sets.SetKind
+
+    """
+    def __new__(cls, element_kind=NumberKind):
+        obj = super().__new__(cls, element_kind)
+        obj.element_kind = element_kind
+        return obj
+
+    def __repr__(self):
+        return "MatrixKind(%s)" % self.element_kind
+
+
+@Mul._kind_dispatcher.register(_NumberKind, MatrixKind)
+def num_mat_mul(k1, k2):
+    """
+    Return MatrixKind. The element kind is selected by recursive dispatching.
+    Do not need to dispatch in reversed order because KindDispatcher
+    searches for this automatically.
+    """
+    # Deal with Mul._kind_dispatcher's commutativity
+    # XXX: this function is called with either k1 or k2 as MatrixKind because
+    # the Mul kind dispatcher is commutative. Maybe it shouldn't be. Need to
+    # swap the args here because NumberKind does not have an element_kind
+    # attribute.
+    if not isinstance(k2, MatrixKind):
+        k1, k2 = k2, k1
+    elemk = Mul._kind_dispatcher(k1, k2.element_kind)
+    return MatrixKind(elemk)
+
+
+@Mul._kind_dispatcher.register(MatrixKind, MatrixKind)
+def mat_mat_mul(k1, k2):
+    """
+    Return MatrixKind. The element kind is selected by recursive dispatching.
+    """
+    elemk = Mul._kind_dispatcher(k1.element_kind, k2.element_kind)
+    return MatrixKind(elemk)