feat(#2936): update Radio component for V2

[twjeffery]

Summary

Updates the Radio component (RadioGroup + RadioItem) to support V2 design
system styling while maintaining full backward compatibility with V1. This
is a Token+CSS+Logic implementation due to the fundamental visual
pattern change requiring DOM structure updates.

Changes

RadioGroup Component

New Props:

• version ("1" | "2", default "1"): Controls V1 vs V2 styling
• size ("default" | "compact", default "default"): Controls
  spacing between radio items

Size Variants:

• Default vertical gap: 16px (unchanged from V1)
• Compact vertical gap: 12px (new)
• Default horizontal gap: 32px (increased from 24px)
• Compact horizontal gap: 24px (new)

Implementation:

• Version and compact state passed to RadioItem children via event
  messaging
• Reactive block ensures size/version changes propagate immediately
• CSS scoped with .v2.compact for V2-only features

RadioItem Component

Visual Pattern Change (V1 → V2):

V1 Approach (Border-Based):

• Uses thick 7px border to create "filled circle" appearance when checked
• Simple DOM structure: .icon div directly in label

V2 Approach (Border + Inner Dot):

• Uses thin 1.5px border + separate 16px inner dot element when checked
• Enhanced DOM structure: .icon-wrapper > .icon + .icon-inner
  (conditional)
• Inner dot absolutely positioned and centered using transform: translate(-50%, -50%)

New Props:

• version (received from RadioGroup): Controls V1/V2 rendering
• compact (received from RadioGroup): Controls typography sizing

State Styling Updates:

All interaction states properly tokenized across 12+ combinations:

• Unchecked: default, hover, focus, hover+focus, disabled
• Checked: default, hover, focus, hover+focus, disabled
• Error states: unchecked + checked with all interaction combinations

V2-Specific Features:

• Inner dot colors: Blue (default), dark blue (hover), grey (disabled),
  red (error)
• Background colors: Light grey (disabled), light red (error), pink (error
  hover)
• Gap spacing: 12px icon-to-label (default), 8px (compact)
• Typography: Medium weight (500), 22px line-height

Size Variants:

• Default: 18px label, medium weight
• Compact: 16px label, medium weight

Related

• Parent issue: Design system 2.0 coded component update #2998
• Component issue: Radio input 2.0 update #2936
• Design tokens PR for Radio
• Figma component