Fix favicon: support JPG/WebP/GIF, add logging, fix path resolution

- Support all common image formats (PNG, JPEG, GIF, WebP, BMP)
  not just PNG — uses getimagesize() to detect type
- Add Log::add() warnings when generation fails (GD missing,
  file not found, unsupported format)
- Fix source path: try both direct path and images/ prefix
  to handle Joomla media field variations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/index.php

@@ -71,7 +71,13 @@ $templatePath = 'media/templates/site/mokocassiopeia';
 $faviconHeadTags = '';
 if ($params_favicon_source) {
     require_once __DIR__ . '/helper/favicon.php';
-    $faviconSourceAbs = JPATH_ROOT . '/' . ltrim($params_favicon_source, '/');
+    // Joomla's media field may return 'images/file.png' or just 'file.png'
+    $faviconSourceRel = ltrim($params_favicon_source, '/');
+    $faviconSourceAbs = JPATH_ROOT . '/' . $faviconSourceRel;
+    // If not found, try prepending images/
+    if (!is_file($faviconSourceAbs) && !str_starts_with($faviconSourceRel, 'images/')) {
+        $faviconSourceAbs = JPATH_ROOT . '/images/' . $faviconSourceRel;
+    }
     $faviconOutputDir = JPATH_ROOT . '/images/favicons';
     $faviconUrlBase   = Uri::root(true) . '/images/favicons';