feat: add estimated codebase size badge to top repositories card

[harshitanagpal05]

Description

Closes #2601

Adds a compact, non-intrusive codebase size badge (Small Codebase / Medium Codebase / Large Codebase) to each repository entry on the Top Repositories dashboard card. The classification is derived from the total language byte count already returned by the GitHub Languages API — no additional API calls are needed.

Thresholds

Total Language Bytes	Label
< 50 KB	Small Codebase
50 KB – 500 KB	Medium Codebase
> 500 KB	Large Codebase

Changes

New file: src/lib/codebase-size.ts

• Pure helper utility with zero dependencies
• getCodebaseSize(totalBytes) — maps raw byte count → "Small" | "Medium" | "Large"
• getCodebaseSizeFromLanguages(languages[]) — convenience wrapper that sums bytes from an existing RepoLanguage[] array and returns the size category (or null when no language data is available)

Modified: src/components/TopRepos.tsx

• Imports the new codebase size utility
• Computes codebaseSize per repo inside the RepoItem component
• Renders a color-coded pill badge inline with existing language pills (same flex flex-wrap container):
  • 🟢 Small — emerald-tinted badge
  • 🟡 Medium — amber-tinted badge
  • 🔵 Large — blue-tinted badge
• Badge only renders when repo.languages has byte data (non-intrusive)
• Includes descriptive aria-label and title attributes for accessibility

Acceptance Criteria

• Visually non-intrusive metadata addition
• Accessible aria-label attributes for screen readers describing repo size scale
• No regression or layout breaking across mobile responsive views (uses existing flex-wrap)
• No additional API calls — uses existing language byte data
• Lint clean (eslint)
• Type-check clean (tsc --noEmit)

Feature Area

Goal Tracker — Top Repositories Card

[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[Priyanshu-byte-coder]

Thanks for contributing! We are currently in a code cleanup sprint and not accepting new features. Please see: #2651

This PR will be revisited once the sprint ends. Tests, refactors, bug fixes, and documentation are welcome in the meantime.