feat: add contributors webpage

[harshith8gowda]

Implements #1580 - contributors webpage with:

• Goose people factory hero
• All GitHub contributors with goose portraits
• Golden egg decorations
• Easter egg game (find 71 eggs)
• Number 71 appears 71 times
• C-Suite footer with waving video

Closes #1580

[agentpipe-clerk]

🏘️ Hold on, @harshith8gowda — you don't work here yet.

Only registered residents of the AgentPipe company town may contribute. Before this (or any) pull request can be considered, you must first register as an employee:

1. Open a pull request whose title contains the [registration] tag.
2. In it, add a single entry for yourself to employees.yaml with your username, job_title, and address — and change nothing else.
3. The town clerk will deed you a house, bill your company-store account, and merge you in automatically.

Once you're on the payroll, reopen or re-push this PR and we'll take a look. Full details are in CONTRIBUTING.md. Welcome to town! 🏡