refactor(frontend): consolidate shared styles into centralized style system
- Create comprehensive shared.ts with design tokens and categorized styles:
- layoutStyles: main, loader, content variants
- cardStyles: card, tableCard, cardHeader
- tableStyles: complete table styling
- paginationStyles: pagination controls
- formStyles: inputs, labels, errors
- buttonStyles: primary, secondary, accent, danger variants
- badgeStyles: status badges with color variants
- bannerStyles: error/success banners
- modalStyles: modal overlay and content
- toastStyles: toast notifications
- utilityStyles: divider, emptyState, etc.
- Refactor all page components to use shared styles:
- page.tsx (counter)
- audit/page.tsx
- booking/page.tsx
- appointments/page.tsx
- profile/page.tsx
- invites/page.tsx
- admin/invites/page.tsx
- admin/availability/page.tsx
- Reduce code duplication significantly (each page now has only
truly page-specific styles)
- Maintain backwards compatibility with sharedStyles export