Enhance filter retrieval: update get_filter API to return full filter lists and modify frontend to utilize them for improved item filtering

Web/templates/main.html

@@ -665,18 +665,30 @@
         // Set up schedule form submission
         setupScheduleFormSubmission();
         
-        // Fetch user status to get current username
-        fetch('/user_status')
-            .then(response => response.json())
-            .then(data => {
-                currentUsername = data.username;
+        // Fetch user status to get current username and full filter lists
+        Promise.all([
+            fetch('/user_status').then(response => response.json()),
+            fetch('/get_filter').then(response => response.json()),
+        ])
+            .then(([userData, filterData]) => {
+                currentUsername = userData.username;
+                if (filterData.filter1) {
+                    allFilter1Values = new Set(filterData.filter1.filter(value => value && typeof value === 'string' && value.trim() !== ''));
+                }
+                if (filterData.filter2) {
+                    allFilter2Values = new Set(filterData.filter2.filter(value => value && typeof value === 'string' && value.trim() !== ''));
+                }
+                if (filterData.filter3) {
+                    allFilter3Values = new Set(filterData.filter3.filter(value => value && typeof value === 'string' && value.trim() !== ''));
+                }
+
                 // Now load items with username information
                 loadItems();
                 // Setup card images display after a short delay to ensure items are loaded
                 setTimeout(setupCardImagesDisplay, 500);
             })
             .catch(error => {
-                console.error('Error fetching user status:', error);
+                console.error('Error fetching user status or filters:', error);
                 loadItems(); // Load items anyway in case of error
             });
 
@@ -721,6 +733,10 @@
         filter3: []
     };
 
+    let allFilter1Values = new Set();
+    let allFilter2Values = new Set();
+    let allFilter3Values = new Set();
+
     // Add this line to define allItems globally
     let allItems = [];
 
@@ -1083,10 +1099,10 @@
                     }
                 });
                 
-                // Populate filter options
-                populateFilterOptions('filter1-options', [...filter1Values].sort(), 1);
-                populateFilterOptions('filter2-options', [...filter2Values].sort(), 2);
-                populateFilterOptions('filter3-options', [...filter3Values].sort(), 3);
+                // Populate filter options using server-provided full filter lists when available.
+                populateFilterOptions('filter1-options', allFilter1Values.size ? [...allFilter1Values].sort() : [...filter1Values].sort(), 1);
+                populateFilterOptions('filter2-options', allFilter2Values.size ? [...allFilter2Values].sort() : [...filter2Values].sort(), 2);
+                populateFilterOptions('filter3-options', allFilter3Values.size ? [...allFilter3Values].sort() : [...filter3Values].sort(), 3);
                 
                 // Start display from leftmost position on full reload only.
                 if (!append) {