Easy SVG changelog

Everything is opt-in. SVG uploads and the icon library start switched off and are turned on under Icons → Settings. Sites that already used SVG uploads keep them.

• Every SVG is sanitized on every way in: media uploader, REST API, WP-CLI and media_sideload_image(), with a safety net for attachments created by other code.
• The icon library: keep your own icons and use them in the WordPress Icon block, with the [easy_svg_icon] shortcode or easy_svg_icon().
• Structural limits checked before sanitizing, so a small file cannot keep a server busy for minutes.
• External references are removed by default.
• A documented add-on surface: easy_svg_sanitizer(), version constants and the Icons panel extension points.