make namedTupleCanEqual stable

[bishabosha]

Fixes #26242

How much have you relied on LLM-based tools in this contribution?

Not at all

How was the solution tested?

Covered by existing tests (this is a refactoring)

[WojciechMazur]

Shouldn't this go through @preview stage first?

[bishabosha]

Shouldn't this go through @preview stage first?

Cc @Gedochao @tgodzik
@WojciechMazur someone should make this process crystal clear in a document because i am seeing conflicting messages e.g. #24675 (comment)

e.g. https://nightly.scala-lang.org/docs/contributing/procedures/contributing-to-stdlib.html says nothing about preview/experimental

Edit:
if i go back to 3.7.0 release notes it does seem to suggest that new API should be experimental and then preview @sjrd (https://scala-lang.org/news/3.7.0/#preview-features)

[odersky]

The preview scheme looks very heavy for library changes. Preview is primarily for tooling to catch up, but library changes should have no bearance on tooling. So I tend to think preview is not necessary for library changes.

[Gedochao]

The current default is for language features to spend one minor series in @preview after being promoted from @experimental, but before making them stable. There can, of course, be exceptions, but those should be run by Scala Core.

if i go back to 3.7.0 release notes it does seem to suggest that new API should be experimental and then preview @sjrd (https://scala-lang.org/news/3.7.0/#preview-features)

Yeah, I would also assume this should apply to new API, as well.

That said, I do agree this is heavy for library changes, so perhaps we can skip this step by default here.
I imagine there could be library changes we would like to put through @preview in the future, but likely not this one.

someone should make this process crystal clear in a document because i am seeing conflicting messages

Yeah, this is fair. Let's touch on this on this week's Scala Core.
We might need a dedicated doc.
cc @SethTisue this might be relevant to documenting features as per scala/scala-lang#1926