Add server-side image thumbnails (sharp): /uploads/thumb/<name> route, ?thumb=1 on file endpoints, disk-cached 480px WebP previews; grids now load thumbnails with lazy loading

public/js/dashboard.js

@@ -56,7 +56,7 @@ function renderRecent(rows) {
   el.innerHTML = rows.map(e => `
     <div class="recent-item">
       ${e.photo_path
-        ? `<img src="${API}${e.photo_path}" data-img="${API}${e.photo_path}" alt="">`
+        ? `<img src="${thumbSrc(e.photo_path)}" data-img="${API}${e.photo_path}" loading="lazy" decoding="async" alt="">`
         : `<div class="thumb"><i data-lucide="graduation-cap"></i></div>`}
       <div class="r-info">
         <div class="r-name">${esc(e.student_name)}</div>
@@ -95,7 +95,7 @@ function renderPhotos(rows) {
   if (!rows.length) { el.innerHTML = '<div class="dash-empty">Фото групп пока нет</div>'; return; }
   el.innerHTML = rows.map(p => `
     <div class="dash-photo" title="${esc(p.group_name)}">
-      <img src="${API}${p.photo_path}" data-img="${API}${p.photo_path}" alt="">
+      <img src="${thumbSrc(p.photo_path)}" data-img="${API}${p.photo_path}" loading="lazy" decoding="async" alt="">
       ${p.caption ? `<div class="pcap">${esc(p.caption)}</div>` : ''}
     </div>`).join('');
 }