[ty] Preserve receiver constraints when binding overloaded methods (#27038)
## Summary
Follow-up to [the receiver-constraint review discussion in
#24707](https://github.com/astral-sh/ruff/pull/24707#discussion_r3326577303).
Prior to this change, we reduced overload receiver matching to a boolean
before binding the method. That kept overloads with satisfiable generic
receivers, but discarded the constraints needed to specialize the
remainder of the signature; structural receivers with contradictory
constraints could also remain visible.
We now reuse the receiver constraint set produced during binding,
existentially prune impossible overloads, and solve exact receiver
bounds into the bound signature while retaining one-sided constraints
for later callable comparisons. For example:
```py
from typing import overload
class Box[T]:
value: T
@overload
def method[S](self: "Box[S]", value: S) -> S: ...
@overload
def method(self, value: bytes) -> bytes: ...
def method(self, value: object) -> object: ...
reveal_type(Box[str]().method)
# Overload[(value: str) -> str, (value: bytes) -> bytes]
```
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
ruff
6c660d8d - [ty] Preserve receiver constraints when binding overloaded methods (#27038)
