feat: add empty state to StreakTracker when no contribution data

[srinidhi-2006-bit]

Summary

Added a friendly empty state to StreakTracker when contribution data is unavailable to improve user experience and avoid displaying misleading empty statistics.

Closes #204

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

Changes Made

• Added empty-state UI when contribution data is missing
• Added informative message and GitHub link
• Preserved layout height to avoid visual shifts
• Used project CSS variables for styling consistency
• Added secure external link handling

How to Test

1. Open the StreakTracker component
2. Simulate empty or missing contribution data
3. Verify the empty-state message appears
4. Verify the GitHub button opens correctly
5. Confirm layout spacing remains stable

Screenshots (if UI change)

N/A

Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

[vercel]

@srinidhi-2006-bit is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Priyanshu-byte-coder]

Good empty state! One small fix — the CTA button text uses text-[var(--background)] which would be invisible in light mode (white text on light background). Use text-[var(--accent-foreground)] instead:

className="mt-4 rounded-md bg-[var(--accent)] px-4 py-2 text-sm font-medium text-[var(--accent-foreground)] transition-opacity hover:opacity-90"

Fix and push — will merge.

[srinidhi-2006-bit]

Updated the CTA button text color to use text-[var(--accent-foreground)] for proper visibility across both light and dark themes.

Pushed the requested fix. Thank you for the review!

[Priyanshu-byte-coder]

CSS vars are now correct. One formatting fix needed:

Indentation of the new if block
The block uses 4-space indentation for the outer if, inconsistent with the rest of the file which uses 2 spaces:

// current (wrong indentation)
    if (
    !contributionData ||

// should be
  if (
    !contributionData ||

Also remove the blank line that was deleted before the block (the diff removes a \n that should stay). After fixing indentation this is ready to merge.

[Priyanshu-byte-coder]

1. Add blank line before const MILESTONES — closing } of the empty-state block and the constant declaration are jammed together.

2. Edge case — the check Object.keys(contributionData.data).length === 0 misses users who have data keys but all values are 0. Consider also guarding on contributions.total === 0, or document why you don't.

3. Checklist incomplete — confirm npm run lint and npm run type-check pass locally before resubmitting.

[srinidhi-2006-bit]

Fixed the requested changes:

• Added proper blank line before const MILESTONES for consistent formatting
• Improved empty-state condition to also handle cases where contribution values are all 0
• Verified both npm run lint and npm run type-check pass locally

Thanks for the detailed review!