feat: add NGO impact dashboard with metrics & visualization

[adityasingh-0803]

✨ Summary

This PR introduces a new Impact Dashboard to NGOWorld, enabling NGOs to display and manage key impact metrics with visualisations, improving transparency and engagement.

🧩 Features Added

• Backend: Data model for impact metrics + API endpoints (GET /api/ngo/:id/impact, POST /api/ngo/:id/impact)
• Frontend: Dashboard on NGO profile pages with charts (funds raised, volunteers, projects, geographies)
• Documentation updated describing how to use, update and view metrics
• Tests added for the new endpoints and UI components

🌱 Why This Helps

• Helps NGOs tell their story with data and visuals – increasing donor/user trust
• Makes NGOWorld more interactive and attractive for contributors and users
• Adds new dimension beyond basic listing of NGOs – gives measurable outcomes

🔍 Future Enhancements

• Add map visualisations for geographic spread of projects
• Role-based editing & approval workflows for metrics
• Export options – CSV or PDF summary
• More advanced analytics: year-on-year trends, benchmarks

Please review when convenient — happy to refine visuals or API as needed.

[github-actions]

Hello @adityasingh-0803, thank you for raising the issue.

Currently, the issue is marked as status: todo ⏳ This issue is yet to be seen by the maintainer of the project. so please wait until the maintainers/owner review it and provide you with feedback/suggestions to proceed further.

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