feat: implement global loading and error states (#76)

[shruthideepikareddy]

Description

This PR implements root-level loading and error handling states using Next.js built-in loading.tsx and error.tsx conventions. It significantly improves the "perceived performance" by providing a consistent, branded UI during navigation and a robust fallback for unexpected errors.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• UI/UX improvement
• Content update
• Chore/maintenance

Closes #76

Changes Made

Please list the specific changes made in this PR:

Global Loading State: Added src/app/loading.tsx featuring a premium animated background and "Syncing Data" indicator.

Global Error Boundary: Added src/app/error.tsxwith a recovery UI ("Try Again" and "Back to Home") and specific styling for error alerts.

Leaderboard Skeleton: Added a specialized LeaderboardSkeleton component and integrated it into the leaderboard route for a smoother data-fetching experience.

Testing Done

Please describe how you tested your changes:

• Tested in development mode (npm run dev)
• Tested production build (npm run build && npm start)
• Tested on multiple browsers (list them)
• Tested on mobile devices/responsive design
• Ran linting (npm run lint)
• Checked for console errors

Screenshots (if applicable)

Checklist

IMPORTANT: Please ensure all items are checked before submitting. PRs that don't follow these guidelines may be closed.

• I have read and followed all guidelines in CONTRIBUTING.md
• I have used the correct branch naming convention (feature/, fix/, docs/, etc.)
• My commits follow Conventional Commits format (feat:, fix:, docs:, etc.)
• I have performed a self-review and tested my changes thoroughly
• CRITICAL: I confirm ONLY my intended changes are included (no unrelated changes, debug code, or breaking changes)
• I have updated relevant documentation if needed
• I have tested the production build locally
• My changes are responsive and work on mobile devices

Additional Notes

Any additional information that would be helpful for reviewers?

---

Remember: Quality over quantity. A well-tested, properly documented small PR is better than a large, rushed contribution.

For more details, please refer to our Contributing Guidelines.

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Project	Deployment	Actions	Updated (UTC)
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[akash-kumar-dev]

Everything looks good to merge. Thanks @shruthideepikareddy for your valuable contributions!