Disable Jekyll processing for GitHub Pages deployment

Add enable_jekyll: false to prevent GitHub Pages from processing
MkDocs-generated site with Jekyll, which was causing build failures.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: jontsai

.github/workflows/deploy-docs.yml

@@ -37,3 +37,4 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./site
+          enable_jekyll: false