fix(filters): give the category tree selectable values, and drive both controls by search (#139)

Three things the e2e run found.

`toTreeData` still emitted `key`, which is how an antd `Tree` identifies a node and not how a `TreeSelect` selects one. Nothing could be picked, and `treeNodeFilterProp="title"` had nothing to filter against. It now emits `value`, matching the admin's CategoryTreeSelect.

The page object typed the name before clicking it, in both controls. Not for realism: the option lists are virtualized, so against a database holding hundreds of categories the wanted row never renders until a search narrows to it, and scrolling to it would be testing the virtual list rather than the filter.

Tag options are matched by class rather than by role, for the reason AdminInventory.toggleStatus already records — antd renders an invisible role="listbox" shim beside the real list, so getByRole('option') resolves to something zero-sized that can never be clicked. The drawer's own title is a plain element rather than a heading, so the click that closes an option list lands on the Favorites heading instead.

The multi-category URL assertion accepts the comma either percent-encoded or literal. URLSearchParams encodes it, which is how the `tags` parameter has always looked, and both spellings parse.

frontend/src/components/FilterDrawer.tsx

@@ -8,7 +8,6 @@ import InputNumber from 'antd/es/input-number';
 import Empty from 'antd/es/empty';
 import Switch from 'antd/es/switch';
 import Grid from 'antd/es/grid';
-import type { DataNode } from 'antd/es/tree';
 import type { FilterOptions } from '../api';
 import { ItemFilters, buildCategoryTree, CategoryNode } from '../filters';
 
@@ -22,9 +21,18 @@ type Props = Readonly<{
   resultCount: number;
 }>;
 
-function toTreeData(nodes: CategoryNode[]): DataNode[] {
+// `value` rather than `key`: this fed an antd `Tree`, which identifies nodes by
+// key, and now feeds a `TreeSelect`, which selects and searches by value. The
+// shape matches the admin's CategoryTreeSelect so the two stay comparable.
+interface CategoryTreeOption {
+  value: number;
+  title: string;
+  children?: CategoryTreeOption[];
+}
+
+function toTreeData(nodes: CategoryNode[]): CategoryTreeOption[] {
   return nodes.map((node) => ({
-    key: node.id,
+    value: node.id,
     title: node.name,
     children: node.children.length ? toTreeData(node.children) : undefined
   }));