docs: add GitHub Pages documentation site

[xulek]

Summary

Adds a complete GitHub Pages documentation site for PyVNCServer using MkDocs Material.

Included

• polished landing page with responsive custom styling and project logo
• installation and quick-start guide
• full TOML configuration reference based on the current safe defaults
• UltraVNC compatibility guide, including Tight/RRE troubleshooting
• noVNC/WebSocket guide updated for the web/noVNC Git submodule
• encoding reference
• security/deployment guide
• CLI and Python API reference
• architecture and performance documentation
• troubleshooting and development guides
• light/dark theme, search, Mermaid diagrams and code-copy support
• GitHub Pages workflow with strict MkDocs builds on PRs and deployment from main

GitHub Pages

After merge, configure Settings → Pages → Build and deployment → Source → GitHub Actions if the repository is not already using Actions as its Pages source.

The expected documentation URL is:

https://xulek.github.io/PyVNCServer/

Validation

The branch is documentation-only. The workflow runs mkdocs build --strict before deployment. Local dependency installation could not be executed in the ChatGPT container because that runtime has no PyPI/network access; GitHub-hosted runners will perform the strict build.

Note: main received the noVNC submodule commit after this branch was created. The documentation already reflects that new submodule setup; the branch changes do not overlap the .gitmodules/submodule commit.