UI/UX: Implement unified EmptyState component for stats page

[tom2drum]

Description and Related Issue(s)

Resolves #3110

This PR implements a unified EmptyState component for displaying empty states across the application, specifically addressing the stats page "coming soon" case. The new component replaces the previous ComingSoon and EmptySearchResult components with a more flexible and reusable solution.

Proposed Changes

• Created a new EmptyState component in toolkit/chakra/empty-state.tsx with support for three types: query, stats, and coming_soon
• Added SVG icons for each empty state type (empty_state_coming_soon.svg, empty_state_query.svg, empty_state_stats.svg)
• Removed deprecated ComingSoon and EmptySearchResult components
• Updated 50+ components across the codebase to use the new EmptyState component
• Added empty state recipe to the theme system for consistent styling
• Created showcase page demonstrating all empty state variants

Breaking or Incompatible Changes

None. The changes are backward compatible as the new component provides the same functionality with improved flexibility.

Additional Information

The new EmptyState component supports:

• Custom titles and descriptions
• Three predefined types with default messaging
• Custom icons
• Consistent styling through theme recipes
• Proper accessibility attributes

Checklist for PR author

• I have tested these changes locally.
• I added tests to cover any new functionality, following this guide
• Whenever I fix a bug, I include a regression test to ensure that the bug does not reappear silently.
• If I have added, changed, renamed, or removed an environment variable
  • I updated the list of environment variables in the documentation
  • I made the necessary changes to the validator script according to the guide
  • I added "ENVs" label to this pull request