refactor: update content structure and layout templates

- Updated author format in content files
- Added section field to content files
- Simplified categories format
- Removed no-category.html layout
- Updated list.html and single.html layouts
- Updated index.html layout
- Updated generate-content.js script
- Do not index content with git

.gitignore

@@ -160,7 +160,7 @@ dist
 
 # WordPress fetched content (auto-generated, should not be committed)
 /data/wordpress/
-/content/posts/
-!content/posts/.gitkeep
+/content/
+!content/.gitkeep
 hugo_stats.json