refactor(github): split getFullDashboardData into focused sub-functions

[JhaSourav07]

🧩 Background

getFullDashboardData in lib/github.ts is ~120 lines handling profile mapping, language aggregation, developer score, insights, achievements, and commit clock — all in one function. This makes it hard to test or reuse individual parts.

🎯 Objective

Extract at least three pure helpers:

• buildProfileData(profileData, totalStars, developerScore)
• aggregateLanguages(repos)
• buildInsights(streakStats, languages)

📁 Files to touch

• lib/github.ts

🛠️ Implementation steps

• Extract each helper, keeping existing tests green.
• Export helpers for unit-testability.
• Add at least one focused test per helper in lib/github.test.ts.

✅ Definition of done

• getFullDashboardData is ≤60 lines.
• Each helper is independently testable.
• All existing tests pass.

[RavindiFernando]

Hi, I am a GSSoC 2026 contributor and would like to work on this.

[surya0904shankar]

/assign surya0904shankar

[Pratikshya32]

Hello @JhaSourav07! /claim

[manya302]

/claim

[github-actions]

✅ Successfully assigned issue to @manya302

💡 Please read CONTRIBUTING.md if you haven't already. Good luck! 🚀