Add bulk selection functionality for filter options in admin templates

Web/templates/main_admin.html

@@ -2847,6 +2847,11 @@ document.addEventListener('DOMContentLoaded', ()=>{
                         while (select.children.length > 1) {
                             select.removeChild(select.lastChild);
                         }
+
+                        const allOption = document.createElement('option');
+                        allOption.value = '__ALL__';
+                        allOption.textContent = '-- Alle auswählen --';
+                        select.appendChild(allOption);
                         
                         // Add new options - data.values contains the array
                         data.values.forEach(filter => {
@@ -4401,6 +4406,42 @@ document.addEventListener('DOMContentLoaded', ()=>{
         applyFilters();
     }
 
+    function bulkToggleFilterOptions(filterNum, shouldSelect) {
+        const filterKey = `filter${filterNum}`;
+        const checkboxes = Array.from(document.querySelectorAll(`#filter${filterNum}-options input[type="checkbox"]`));
+        if (checkboxes.length === 0) {
+            return;
+        }
+
+        const nextValues = new Set(activeFilters[filterKey]);
+
+        checkboxes.forEach(checkbox => {
+            const value = checkbox.value;
+            const group = checkbox.dataset.group || '';
+            const filterValue = group ? `${group}:${value}` : value;
+            checkbox.checked = shouldSelect;
+
+            if (shouldSelect) {
+                nextValues.add(filterValue);
+            } else {
+                nextValues.delete(filterValue);
+            }
+        });
+
+        activeFilters[filterKey] = Array.from(nextValues);
+        updateSelectedFiltersDisplay(filterNum);
+
+        if (filterNum === 1) {
+            rebuildFilter2Options();
+            rebuildFilter3Options();
+        } else if (filterNum === 2) {
+            rebuildFilter3Options();
+        }
+
+        saveFilterState();
+        applyFilters();
+    }
+
     function populateFilterOptions(containerId, filterValues, filterNum) {
         const container = document.getElementById(containerId);
         if (!container) {
@@ -4408,6 +4449,27 @@ document.addEventListener('DOMContentLoaded', ()=>{
         }
         
         container.innerHTML = '';
+
+        const bulkActions = document.createElement('div');
+        bulkActions.style.display = 'flex';
+        bulkActions.style.gap = '8px';
+        bulkActions.style.marginBottom = '10px';
+
+        const selectAllBtn = document.createElement('button');
+        selectAllBtn.type = 'button';
+        selectAllBtn.className = 'clear-filter';
+        selectAllBtn.textContent = 'Alle wählen';
+        selectAllBtn.onclick = () => bulkToggleFilterOptions(filterNum, true);
+
+        const clearAllBtn = document.createElement('button');
+        clearAllBtn.type = 'button';
+        clearAllBtn.className = 'clear-filter';
+        clearAllBtn.textContent = 'Alle abwählen';
+        clearAllBtn.onclick = () => bulkToggleFilterOptions(filterNum, false);
+
+        bulkActions.appendChild(selectAllBtn);
+        bulkActions.appendChild(clearAllBtn);
+        container.appendChild(bulkActions);
         
         const groupedValues = {};