add Claims empty state, fix RewardsPage claim-all button, add reputat…

[feyishola]

…ion chart, and fix ThemeContext default

Summary

• Add EmptyState component for Claims list when no claims exist

  • Shows informative message with claim creation action
  • Includes appropriate icon and user guidance
  • Adds unit tests for empty state rendering

• Fix RewardsPage claim-all button state to disable when total rewards = 0

  • Button now disabled with visual indication (opacity, cursor)
  • Shows tooltip explaining why disabled
  • Prevents unnecessary contract calls
  • Adds test coverage for zero rewards scenario

• Add ReputationChart component showing historical score visualization

  • Line chart with 30-day score history
  • Interactive tooltips showing exact scores on hover
  • Color-coded trend indicators (green/red for up/down)
  • Responsive design with mobile support

• Fix ThemeContext default value to prevent undefined on first render

  • Initialize with system preference detection
  • Add default theme fallback ('light')
  • Prevent hydration mismatches in Next.js
  • Add unit tests for context initialization

All changes include comprehensive tests, follow existing design patterns,
and maintain backward compatibility with no breaking changes.

closes #180
closes #181
closes #182
closes #183

[dDevAhmed]

conflicts @feyishola