Add y as inbox archive shortcut alongside a

Both a and y now archive the selected item in the mine tab.
Archive requires selecting an item first with j/k navigation.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/pages/Inbox.tsx

@@ -966,7 +966,8 @@ export function Inbox() {
           setSelectedIndex((prev) => Math.max(prev - 1, 0));
           break;
         }
-        case "a": {
+        case "a":
+        case "y": {
           if (!isMineTab || selectedIndex < 0 || selectedIndex >= itemCount) return;
           e.preventDefault();
           const item = workItemsToRender[selectedIndex];