Fix category filter bug and add tab accessibility

The category tabs were not filtering because the generic tab event handler
was overwriting currentFilter with undefined (category tabs use data-category
not data-filter). Fixed by targeting only [data-filter] tabs and clearing
categoryFilter when switching to non-category tabs.

Added proper ARIA attributes for screen reader accessibility:
- role="tablist" on nav-tabs container
- role="tab" and aria-selected on all tab buttons
- Dynamic aria-selected updates on tab clicks

Also includes API support for category field and deploy script update.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

api.php

@@ -229,24 +229,26 @@ switch ($action) {
 
         $name = sanitize($input['name'] ?? '');
         $container = sanitize($input['container'] ?? 'glass-bail-medium', 50);
+        $category = sanitize($input['category'] ?? 'other', 50);
         $outOfStock = (bool)($input['outOfStock'] ?? false);
 
         if (empty($name)) {
             echo json_encode(['success' => false, 'error' => 'Name required']);
             break;
         }
-        
+
         $inventory = loadInventory();
         $newItem = [
             'id' => getNextId($inventory),
             'name' => $name,
             'container' => $container,
+            'category' => $category,
             'outOfStock' => $outOfStock
         ];
-        
+
         $inventory[] = $newItem;
         saveInventory($inventory);
-        
+
         echo json_encode(['success' => true, 'item' => $newItem]);
         break;
         
@@ -259,31 +261,33 @@ switch ($action) {
         $id = (int)($input['id'] ?? 0);
         $name = sanitize($input['name'] ?? '');
         $container = sanitize($input['container'] ?? '', 50);
+        $category = sanitize($input['category'] ?? '', 50);
         $outOfStock = (bool)($input['outOfStock'] ?? false);
 
         if ($id <= 0) {
             echo json_encode(['success' => false, 'error' => 'Invalid ID']);
             break;
         }
-        
+
         $inventory = loadInventory();
         $found = false;
-        
+
         foreach ($inventory as &$item) {
             if ($item['id'] === $id) {
                 if (!empty($name)) $item['name'] = $name;
                 if (!empty($container)) $item['container'] = $container;
+                if (!empty($category)) $item['category'] = $category;
                 $item['outOfStock'] = $outOfStock;
                 $found = true;
                 break;
             }
         }
-        
+
         if (!$found) {
             echo json_encode(['success' => false, 'error' => 'Item not found']);
             break;
         }
-        
+
         saveInventory($inventory);
         echo json_encode(['success' => true]);
         break;