Syntax highlighting

Syntax highlighting adds language-aware colour to fenced Markdown code blocks in themes that support it.

Name the language after the opening fence:

```php
echo 'Hello';
```

Common language names such as php, javascript, css, html, json, and bash select the matching grammar. An unlabeled or unsupported block remains readable as plain preformatted code. If highlighting is disabled, every fenced block still renders as ordinary preformatted code.

The active theme controls the colour scheme and whether syntax highlighting is shown. All scripts and styles are bundled locally; public pages do not contact a CDN or highlighting service.

Static exports include the local highlight.js assets with the exported theme output.