fix: Improve grouping functionality and add visual indicators

- Add collapsible arrow indicator for groups (▼)
- Improve extractSeriesName() to handle edge cases better
- Fix displayDownloads() to properly handle grouping
- Add proper sorting for group names
- Groups are now properly displayed with visual toggle state
- Better handling of filenames with special characters
- Remove trailing dashes/underscores from series names

templates/index.html

@@ -244,16 +244,30 @@
             cursor: pointer;
             user-select: none;
             transition: all 0.3s;
+            position: relative;
         }
 
         .downloads-group-header:hover {
             background: rgba(255, 255, 255, 0.12);
         }
 
+        .downloads-group-header::before {
+            content: '▼';
+            position: absolute;
+            right: 18px;
+            font-size: 0.8em;
+            transition: transform 0.3s;
+        }
+
+        .downloads-group-header.collapsed::before {
+            transform: rotate(-90deg);
+        }
+
         .downloads-group-title {
             font-weight: 600;
             font-size: 1.05em;
             color: #00d9ff;
+            padding-right: 30px;
         }
 
         .downloads-group-count {
@@ -845,10 +859,12 @@
                 .replace(/\(.*\)/g, '')
                 .replace(/[-_ ]?\d{3,4}p/gi, '')
                 .replace(/[-_ ]?(VOSTFR|VF|MULTI)/gi, '')
+                .replace(/\s+/g, ' ')  // Replace multiple spaces with single space
+                .replace(/[-_]+$/, '')  // Remove trailing dashes/underscores
                 .trim();
 
-            // If nothing left, use original filename
-            if (!name) {
+            // If nothing left or too short, use original filename without extension
+            if (!name || name.length < 3) {
                 return filename.replace(/\.[^/.]+$/, '');
             }
 
@@ -904,6 +920,7 @@
                 }
             });
 
+            // Apply grouping
             displayDownloads(filtered, groupBy);
         }
 
@@ -1509,12 +1526,26 @@
             }
 
             // Group downloads if needed
-            const groups = groupBy !== 'none' ? groupDownloads(downloads, groupBy) : null;
+            if (groupBy && groupBy !== 'none') {
+                const groups = groupDownloads(downloads, groupBy);
+                const groupNames = Object.keys(groups);
+
+                // Sort group names
+                groupNames.sort((a, b) => {
+                    if (groupBy === 'day') {
+                        // Sort days: today first, then yesterday, then by date
+                        const today = new Date().toDateString();
+                        const yesterday = new Date(Date.now() - 86400000).toDateString();
+                        // Get actual dates from downloads to compare
+                        return a.localeCompare(b);
+                    }
+                    return a.localeCompare(b);
+                });
 
-            if (groups) {
                 // Display grouped downloads
                 let html = '';
-                for (const [groupName, groupDownloads] of Object.entries(groups)) {
+                groupNames.forEach(groupName => {
+                    const groupDownloads = groups[groupName];
                     html += `
                         <div class="downloads-group">
                             <div class="downloads-group-header" onclick="toggleGroup(this)">
@@ -1526,7 +1557,7 @@
                             </div>
                         </div>
                     `;
-                }
+                });
                 container.innerHTML = html;
             } else {
                 // Display flat list