overload not accepted as override

```py
from typing import overload, override

class A:
def f(self, x: float = 0.0): ...

class B(A):
@overload
def f(self): ...
@overload
def f(self, x: float): ...
@override
def f(self, x: float = 0.0): ...
```

Start by reproducing the Python snippet with the type checker and confirm that the overload-based override is rejected. Locate the checker path handling @overload and @override, then add a regression test for this example. Done means the shown override is accepted without weakening unrelated override checks.

Written by the indexing model from the issue text.