Fix dashboard sidebar filters not working

JS was querying .filter-group but the HTML uses .lt-filter-group,
so no checkboxes were ever collected and filters had no effect.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/js/dashboard.js

@@ -312,17 +312,17 @@ function initSidebarFilters() {
 
             // Collect selected statuses
             const selectedStatuses = Array.from(
-                document.querySelectorAll('.filter-group input[name="status"]:checked')
+                document.querySelectorAll('.lt-filter-group input[name="status"]:checked')
             ).map(cb => cb.value);
 
             // Collect selected categories
             const selectedCategories = Array.from(
-                document.querySelectorAll('.filter-group input[name="category"]:checked')
+                document.querySelectorAll('.lt-filter-group input[name="category"]:checked')
             ).map(cb => cb.value);
 
             // Collect selected types
             const selectedTypes = Array.from(
-                document.querySelectorAll('.filter-group input[name="type"]:checked')
+                document.querySelectorAll('.lt-filter-group input[name="type"]:checked')
             ).map(cb => cb.value);
 
             // Update URL parameters