[FEATURE]: Add Contributor Profile Page with GSoC Markdown Report Exporter

[AbiramiR-27]

Feature and its Use Cases

Feature Description

In alignment with the project's roadmap in FeatureWishlist.md:

"OrgExplorer could have a profile page for every contributor, showing in summarized and detailed ways, the activity of that contributor in a specified period of time... This profile should be exportable as a markdown file. Contributors could then use this markdown file as a starting point to prepare their final GSoC reports."

I would like to propose adding this dedicated Contributor Profile Page to OrgExplorer. It will allow users to review individual developer contributions over a customized date range (e.g., the GSoC coding period) and export a formatted summary report.

Detailed Breakdown

1. Interactive Date Filter:
   • A date range selector on the profile page to filter commits, PRs, and issues during GSoC or any custom timeline.
2. Activity Metrics & Visualizations:
   • Summary cards displaying key stats (total merged PRs, open issues, total lines changed/commits where available).
   • Visual activity timelines breaking down contribution status.
   • Zero New Dependencies: All visual charts will reuse the existing Recharts configuration and design components already integrated into the project.
3. Markdown Export Action:
   • An "Export as Markdown" button that generates and downloads a .md file containing a clean summary table and itemized list of work accomplished, serving as a ready-to-use template for GSoC final evaluations.

Proposed Architecture Changes

• Routing: Add a /contributors/:username route in Navbar.jsx / App.jsx.
• Analytics Engine: Enhance analytics.js to support date-based filters and compute individual contributor timelines.
• UI: Build src/pages/ContributorProfilePage.jsx reusing the project's existing UI components and chart primitives.

I will raise the pr shortly!

Additional Context

No response

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates