feat: WDS fluid corner radii scale

[ichik]

Analogous with existing scales for innerSpacing, outerSpacing, typography ones. Three steps. Context: we currently use single static --border-radius-1, but for smaller radii we're doing fluid clamping. Better to just have a clean scale. Current components using radius-1 → radius-2. Clamp in checkbox: use radius-1.

Open questions:

• handling the interaction with theme's radius (sharp | round | pill)

• checkbox exception for pill specifically

  The sharp and round options can be simply ratios similar to density and sizing, but pill needs to implement following behavior:

• checkbox has rounded corner, but needs to stay square-ish
• button have 50% corner radius
• cards and stuff above has big radius, but not 50%

[ichik]

Hey team! Please add your planning poker estimate with Zenhub @dhruvikn @jsartisan @KelvinOm @shadabbuchh

[KelvinOm]

Move the task to the backlog so it's not clear how to make fluid tokens for radii now. The behavior of the checkbox is fixed here.

[ichik]

@KelvinOm let's treat this ticket as a research one. I'll do some analysis on what we want to achieve and create follow-ups after that.