[Toolkit][Shadcn] Add Native Select and align Select with upstream

[laurentdav]

Hi!

I opened two PRs to align the Shadcn Select recipes with the current upstream components:

• [Toolkit][Shadcn] Add native-select recipe #3743 adds the dedicated native-select recipe for the styled native HTML control.
• [Toolkit][Shadcn] Align select with shadcn reference #3744 aligns the existing select recipe with the fully custom composite component, including keyboard navigation, typeahead, form support, positioning, scrolling, validation states, and RTL.

#3744 is currently stacked on #3743 so its migrated examples and CI can use NativeSelect. Its diff will reduce automatically once #3743 is merged.