fix: fetch real GitHub contribution data for heatmap instead of Math.random() (#185)

[5hivam123]

Description

Replaced static Math.random() generated heatmap data with real
GitHub contribution data fetched from GitHub Contributions API
using the logged-in user's githubUsername.

Changes:

• Removed static heatmapCells array using Math.random()
• Added useState for heatmapCells initialized to empty
• Added useEffect to fetch real contribution data from
  github-contributions-api.jogruber.de using githubUsername
• Mapped real contribution counts to heatmap color levels (0-4)

Related Issue

Fixes #185

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Screenshots / Videos (if applicable)

[Add screenshot of Dashboard showing real GitHub heatmap data]

Testing Done

• Visual verification on local dev server (http://localhost:5173)
• Heatmap now shows consistent data on refresh ✅
• Heatmap reflects real GitHub contributions ✅
• Falls back gracefully if API fails ✅
• No console errors or warnings

Checklist

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• My changes generate no new warnings or console errors.

Contributor Declaration

• I confirm that this contribution is made under the rules of NSoC 2026.
• I confirm that I have been assigned the related issue by a maintainer before opening this PR.
• I have read the Contributing Guidelines and Code of Conduct.

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Project	Deployment	Actions	Updated (UTC)
ranker-hub	Ready	Preview, Comment	Jun 3, 2026 1:37pm