feat: add printable productivity PDF reports

[KrutagyaKaneria]

📌 Summary

This PR introduces a client-side PDF export feature that allows users to generate and download a professional productivity report directly from their DevTrack dashboard.

The generated report provides a structured summary of a developer's coding activity, making it easy to share progress during performance reviews, mentorship sessions, portfolio showcases, or on professional networks.

Closes #3046

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🚀 Changes Made

📄 PDF Report Generation

• Added a "Download PDF Report" action to the Dashboard.
• Implemented client-side PDF generation using the existing jsPDF package.
• Added reusable PDF generation helper (src/lib/pdf-generator.ts).

📊 Report Contents

The generated report includes:

• User profile information
• Productivity summary
• Weekly and monthly commit statistics
• Current coding streak
• WakaTime activity summary
• Language distribution
• Top repositories
• Goal completion progress
• Achievement highlights (when available)

🎨 Report Design

• Clean professional layout matching the DevTrack design language.
• Proper spacing, typography, and page margins.
• Download-ready PDF suitable for sharing and printing.

⚡ Performance

• Client-side generation (no backend/API changes).
• Fast report generation.
• Graceful handling of missing or unavailable data.
• Reuses existing dashboard state and utilities.

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✅ Testing

Verified:

• Download button is visible on the Dashboard
• PDF downloads successfully
• Report renders correct user information
• Commit statistics display correctly
• WakaTime metrics render when available
• Language distribution is included
• Goal progress is displayed
• Missing data is handled gracefully
• Existing dashboard functionality remains unaffected

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🛠️ Quality Checks

• pnpm lint
• pnpm type-check
• pnpm test
• Project builds successfully

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[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

[KrutagyaKaneria]

@Priyanshu-byte-coder can you review my PR