feat: Add analytics dashboard with performance insights (Phase 3.2)

[Datakult0r]

Summary

This PR implements Phase 3.2 of the PRD - Analytics Dashboard. It adds a comprehensive analytics system with backend API endpoints and a frontend visualization page.

Backend (308 lines): New /api/analytics routes providing dashboard stats, success rates by source, proposal generation times, relevance score distribution, grants by source, and 30-day activity trends.

Frontend (436 lines): New /analytics page with overview stat cards, proposal status distribution, relevance distribution bar chart, generation time comparison (Fast Track vs Research Track), success rate by source, grants by source, and a 30-day trend visualization.

Review & Testing Checklist for Human

• Verify Supabase join syntax - The /success-rate endpoint uses proposals -> grants join. Confirm this works with your schema: grants (source, name) nested select.
• Test with real data - The charts use CSS-based visualizations. Verify they render correctly with actual database content, especially edge cases (0 values, very large numbers).
• Security: Analytics endpoints are unprotected - All /api/analytics/* routes have no authentication. Decide if business metrics should be public or protected.
• Performance with large datasets - The /dashboard endpoint makes 6+ sequential Supabase queries. Test with production-scale data to ensure acceptable response times.

Recommended test plan:

1. Start backend and frontend locally
2. Navigate to /analytics
3. Verify all 6 stat cards show correct counts
4. Check that charts render (may show "No data available" if database is empty)
5. Run the seed script (npm run seed) and refresh to see populated charts
6. Inspect Network tab to verify all 6 API calls succeed

Notes

• This PR is based on the Session 9 branch, so PRs chore: repository cleanup - remove node_modules and resolve merge conflicts #10-18 should be merged first
• Frontend uses Svelte 5 runes ($state) - ensure project is on Svelte 5
• No sidebar navigation link added for /analytics - you may want to add one manually

Link to Devin run: https://app.devin.ai/sessions/9573820f0f6d41dab1cff8a61c26c981
Requested by: @Datakult0r

[devin-ai-integration]

Original prompt from Datakult

https://github.com/Datakult0r/ai-grant-crawler-a2a-pro
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Project	Deployment	Review	Updated (UTC)
ai-grant-crawler-a2a-pro	Error		Jan 25, 2026 9:00pm

[devin-ai-integration]

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