Add a contributor showcase to the Community page

## Background

The refreshed Community page restores the core ways to learn, connect, and contribute. A visual contributor showcase should be designed and delivered separately so the OINK migration stays focused.

## Scope

- Add a bilingual contributor avatar/list section to the Community page.
- Link each visible contributor to their public profile and provide accessible names and image fallbacks.
- Define the included Apache HugeGraph repositories, ordering, update cadence, and a reproducible data-generation process.
- Keep generated data reviewable in the repository; do not call the GitHub API from visitors' browsers.
- Lazy-load avatars and verify CSP, privacy, responsive layout, dark mode, and empty/error states.

## Acceptance criteria

- English and Chinese Community pages present the same contributor set.
- The list is keyboard-accessible and usable without JavaScript.
- Contributor data can be refreshed with a documented command and produces deterministic output.
- CI validates generated data and broken profile/image links.

Follow-up to #466.

Start with the existing English and Chinese Community pages and follow-up issue #466; identify where contributor data and page generation currently live. Define the repository set, ordering, refresh command, deterministic generated output, and CI checks, then verify keyboard and no-JavaScript access, links, fallbacks, responsive and dark-mode behavior, empty/error states, and CSP.

Written by the indexing model from the issue text.