feat: add ConnectedButtonGroup component - #5074

…ty overlay

Pre-blending the disabled container color with color().alpha() breaks on
Android dynamic themes where onSurface is a PlatformColor object rather
than a string — the fallback rendered a fully opaque near-black container.
Apply the MD3 12% disabled opacity as a style on an absolute-fill overlay
instead, which works with any ColorValue. Found during on-device Android
verification.

- tokens: pressed inner corner now morphs sharper than rest (M3
  ConnectedButtonGroup*Tokens: Inner=Small, PressedInner=ExtraSmall), and
  large/extra-large rest inner corners corrected to large(16)/largeIncreased(20).
- press morph: selected buttons also morph on press (pressed precedence over
  checked, matching Compose ToggleButton); pressOut returns to the rest radius.
- accessibility: buttons now use the radio (single-select) / checkbox
  (multi-select) role instead of button+aria-checked, valid on web and better
  announced natively.
- reduce-motion: shape morph honours the reduce-motion setting (ReduceMotion),
  matching Switch/FAB.
- docs: register ConnectedButtonGroup in component-docs.config so the
  deprecation link and generated page resolve.
- tests: cover shape tokens and role semantics (22 total).

- resolve corner shapes through the shared ShapeToken/resolveCornerRadius
  from theme/utils/shape instead of a local re-implementation.
- drop the per-button rippleColor prop and runtime ripple color derivation;
  TouchableRipple's stateLayerPressed default applies, consistent with the
  removal of customRippleColor across components.
- expose background and hitSlop passthroughs per button, mirroring
  SegmentedButtons, and remove the ineffective automatic touch-target
  expansion.
- drive the corner morph with the theme's fast spatial spring (toRawSpring),
  matching Switch and FAB, instead of timing curves.
- add radiogroup semantics to the single-select row and collision-proof
  list keys.
- honour intrinsic button widths in content-sized parents (flexBasis auto).
- export ConnectedButtonGroupSize, register a docs screenshot, keep the
  docs config alphabetical, and extend tests with render snapshots (23).

The docs build requires a committed page under 5.x/docs/components for
every entry in component-docs.config; add the ConnectedButtonGroup page
(usage, props, theme colors) mirroring SegmentedButtons, regenerate the
6.x content, and point the SegmentedButtons deprecation notice at the
correct relative path so the link resolves.