We conventionally avoid the pattern auto variable = Type{args}; because it is strictly more complicated than Type variable{args};. Following this convention reserves auto for the cases where it's doing real work to deduce a type.

We've accumulated a few cases which I'm cleaning up here. (There are a few more cases which I am reluctantly not changing, because auto results in code lining up nicely. I thought about it, though.)

In P2321R2_views_zip, I'm also performing some renames. We can name the parameters single_element_container and three_element_container, as that's relevant to the caller. Then we can rename the local copy to just writable, which avoids wrapping lines.

In <__msvc_int128.hpp>, I'm using static_cast. MSVC emits a signed/unsigned warning if we attempt to directly initialize _Int_max (possibly because numeric_limits::max() is constexpr but not consteval). Since we're intentionally changing the type from int to size_t, it seems stylistically best to emphasize this with a static_cast anyways.