Docs: add ci workflow for building Sealos Docs Site Docker image

[yangchuansheng]

🤖 Generated by Copilot at 79d0e24

Summary

🚀🌐🗜️

This pull request adds a new Dockerfile and a GitHub Actions workflow for building and pushing a Docker image for the Sealos Docs Site. The image uses Docusaurus to generate a static website from the docs source code and nginx-brotli to serve it with compression. The image is pushed to three different registries for convenience.

Docusaurus docs
Build and push Docker image
Winter workflow done

Walkthrough

• Add a new workflow file for GitHub Actions to build and push a Docker image for the Sealos Docs Site (link)
• Add a new Dockerfile for the Sealos Docs Site (link)

[sealos-ci-robot]

🤖 Generated by lychee action

Summary

Status	Count
🔍 Total	956
✅ Successful	375
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	580
❓ Unknown	0
🚫 Errors	0

Full action output

Full Github Actions output

[sweep-ai]

Apply Sweep Rules to your PR?

• Apply: Leftover TODOs in the code should be handled.
• Apply: All new business logic should have corresponding unit tests in the tests/ directory.
• Apply: Any clearly inefficient or repeated code should be optimized or refactored.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!.