perf: optimize category and profile calculation in CategoryFilterWidget

Combine the calculation of activeCategories and uniqueProfiles into a single
useMemo hook that iterates over the shortcuts array once using standard
for loops. This replaces multiple mapping, flatMapping, and spreading operations
which are computationally expensive and trigger garbage collection unnecessarily.

Co-authored-by: alazndy <78882672+alazndy@users.noreply.github.com>

Author: google-labs-jules[bot]

components/CategoryFilterWidget.tsx

@@ -6,12 +6,23 @@ import { UsersIcon } from '@heroicons/react/24/outline';
 export const CategoryFilterWidget: React.FC = () => {
   const { shortcuts, filterCategory, setFilterCategory, filterProfile, setFilterProfile } = useGTab();
 
-  const activeCategories = useMemo(() => {
-    return ['All', ...new Set(shortcuts.map(s => s.category))];
-  }, [shortcuts]);
+  const { activeCategories, uniqueProfiles } = useMemo(() => {
+    const categorySet = new Set<string>();
+    const profileSet = new Set<string>();
+
+    for (const s of shortcuts) {
+      if (s.category) categorySet.add(s.category);
+      if (s.profiles) {
+        for (const p of s.profiles) {
+          if (p.name) profileSet.add(p.name);
+        }
+      }
+    }
 
-  const uniqueProfiles = useMemo(() => {
-    return Array.from(new Set(shortcuts.flatMap(s => s.profiles?.map(p => p.name) || []))).sort();
+    return {
+      activeCategories: ['All', ...categorySet],
+      uniqueProfiles: Array.from(profileSet).sort()
+    };
   }, [shortcuts]);
 
   return (