[Feat] Add Working Groups page to website

## Summary

Add a `/community/work-groups` page to the project website showcasing all Working Groups.

## Requirements

- List all 9 WGs with descriptions and icons
- Show code paths for each WG
- Display current contributors and maintainers (dynamic from GitHub or static for now)
- Link to relevant GitHub issues filtered by WG label
- Match existing website design system

## Reference

- Working Groups definition: #236
- Website codebase: `website/`

## Tech Stack

- React + Vite (same as existing website)
- Tailwind CSS

## Nice to Have

- Auto-sync contributors from GitHub API
- Per-WG activity stats (PRs, issues)

Start in the website/ codebase by reviewing the existing React/Vite pages and Tailwind design system. Use issue #236 for the Working Groups definition, then implement /community/work-groups with all 9 WGs, descriptions, icons, code paths, contributor or maintainer information, and links to WG-filtered GitHub issues. Done means the page matches the existing site and all required WG information is represented; API syncing and activity stats are optional.

Written by the indexing model from the issue text.