show read more button for attachments in sidebar by default

public/s/js/sidebar-activity.js

@@ -441,6 +441,16 @@
         });
     };
 
+    const attachMediaLoadListeners = (element) => {
+        element.querySelectorAll('img, video').forEach(media => {
+            if (media.dataset.loadListenerBound) return;
+            media.dataset.loadListenerBound = 'true';
+
+            media.addEventListener('load', checkOverflow, { once: true });
+            media.addEventListener('loadedmetadata', checkOverflow, { once: true });
+        });
+    };
+
     // Event delegation — read-more expands, see-less collapses
     document.addEventListener('click', (e) => {
         // Read more / See less
@@ -507,6 +517,7 @@
         if (ioSentinel) {
             container.appendChild(ioSentinel);
         }
+        attachMediaLoadListeners(container);
         checkOverflow();
         fetchSidebarYoutubeTitles(container);
         // Auto-play converted GIF videos
@@ -514,7 +525,7 @@
         return true;
     };
 
-    const SIDEBAR_PAGE_LIMIT = 50;
+    const SIDEBAR_PAGE_LIMIT = 5;
 
     const loadActivity = async (silent = false) => {
         const container = document.getElementById('sidebar-activity-container');
@@ -613,6 +624,7 @@
                     }
                     // Keep the IO sentinel at the very end so it triggers on the next scroll
                     if (ioSentinel) container.appendChild(ioSentinel);
+                    attachMediaLoadListeners(container);
                     checkOverflow();
                     fetchSidebarYoutubeTitles(container);
                     // Auto-play converted GIF videos
@@ -661,6 +673,7 @@
             if (node) {
                 node.classList.add('new-item-fade');
                 container.prepend(node);
+                attachMediaLoadListeners(node);
                 checkOverflow();
                 fetchSidebarYoutubeTitles(container);
             }
@@ -701,6 +714,7 @@
                     el.classList.remove('new-item-fade');
                     void el.offsetWidth;
                     el.classList.add('new-item-fade');
+                    attachMediaLoadListeners(inner);
                     checkOverflow();
                     fetchSidebarYoutubeTitles(el);
                     // Auto-play converted GIF videos