[match-case] mypy ignores missing `@runtime_checkable` in class-pattern

from typing import Any, Callable, Protocol, runtime_checkable

class Proto(Protocol):
    def foo(self, x: int, /) -> object: ...

def test_object(x: object) -> None:
    match x:
        case Proto() as y:  # No Error
            reveal_type(y)  # N: Revealed type is "__main__.Proto"

    if isinstance(x, Proto):  # E: Only @runtime_checkable protocols ...
        reveal_type(x)  # N: Revealed type is "__main__.Proto"

https://mypy-play.net/?mypy=latest&python=3.12&gist=6e3f280e71d3cb4d6131e51496370f97

Reproduce the minimal Python 3.12 example from the issue in the linked mypy-playground, comparing the class-pattern behavior with the isinstance check. Trace mypy's match-case analysis for protocol patterns; done means a missing @runtime_checkable protocol is diagnosed consistently with isinstance.