implicit override not reported for overloaded methods without implementation

Overloaded methods without implementation (i.e. in a `Protocol` or a `.pyi`) are not flagged when using `reportImplicitOverride=true` if they override a method but not decorated as such:

```py
from typing import Literal, Protocol, overload

class BoolFormatter(Protocol):
def format_bool(self, b: bool, /) -> str: ...

class LiteralBoolFormatter(BoolFormatter, Protocol):
@overload
def format_bool(self, b: Literal[True], /) -> Literal["⊤"]: ...
@overload
def format_bool(self, b: Literal[False], /) -> Literal["⊥"]: ...
@overload # I'll open another issue for this
def format_bool(self, b: bool, /) -> Literal["⊤", "⊥"]: ...
```

[playground](https://pyright-play.net/?pythonVersion=3.14&strict=true&reportImplicitOverride=true&code=GYJw9gtgBALgngBwJYDsDmUkQWEMoAySMApiAIYA2ANFAArgxgDGYNUYAbmZWOQCYAoQc0rkAzuKgAhMGwBiuCORikQACgZgmrSgEoAXIKgmo-EsCjAlKgPoAjOZXXiSlYLXsGojtrQD0elAAtAB8UOIwIN4AdHHCohJSRGpUsgo2qmTq6ZSKIMpZILRaOmyGxqYAAlw8fEKmZhZWmQ5OLm4ePt4pZFQA2gAqIACuJAC6AUFhhMR9lP0ARIAlRIvjsfGNNdwgvAKVJuaW1gV2vs6u7p49cxQL8lSuk1CBIeG9d0uApURrGzEHUG2dQEJgAxFAAJIAckolA4CBIKCg5BQ2gAFmRMJIxi0QLA0UgpACjrjCm02B0rt0fE4pm9ZqkFitFrRFj91lA4jEgA)

In a `.pyi` this false negative also occurs outside of a `Protocol`:

```pyi
from typing import Literal, overload

class BaseFormatter:
def format_bool(self, b: bool, /) -> str: ...

class Formatter(BaseFormatter):
@overload
def format_bool(self, b: Literal[True], /) -> Literal["⊤"]: ...
@overload
def format_bool(self, b: Literal[False], /) -> Literal["⊥"]: ...
@overload
def format_bool(self, b: bool, /) -> Literal["⊤", "⊥"]: ...
```

Start with the linked pyright-play.com reproduction and compare the Protocol example with the .pyi example while reportImplicitOverride is enabled. Trace how overloaded declarations without implementations are checked, then verify that both cases report the missing implicit override without changing unrelated overload behavior.

Written by the indexing model from the issue text.