Rework lazy loading as js controlled fetches

src/Output.php

@@ -88,7 +88,7 @@ class Output
                 $caption = $label;
             }
 
-            // Build thumbnail URL - rely on native loading="lazy" for deferred loading
+            // Build thumbnail URL - JavaScript will load via fetch() for cancellability
             $thumbUrl = $this->withQueryParams($url, [
                 'thumb' => 1,
                 'w' => $genThumbW,
@@ -107,12 +107,10 @@ class Output
                 . '>';
             $renderer->doc .= '<img'
                 . ' class="luxtools-thumb"'
-                . ' src="' . $thumbSrc . '"'
+                . ' data-src="' . $thumbSrc . '"'
                 . ' alt=""'
                 . ' width="' . $thumbW . '"'
                 . ' height="' . $thumbH . '"'
-                . ' loading="lazy"'
-                . ' decoding="async"'
                 . ' />';
             $renderer->doc .= '<span class="luxtools-gallery-caption">' . $caption . '</span>';
             $renderer->doc .= '</a>';