Add comprehensive accessibility support across shared packages:
- A11y store with contrast, colorblind mode, and reduce motion settings
- A11yQuickToggles and A11ySettings UI components
- PillNavigation and PillDropdown components in shared-ui
- Calendar app updates to integrate new theme/a11y features
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>