fix: PatternExplorer — exclude root id from node paths so they match taxonomy_path

enrichTree was building paths starting with 'root', but patterns store paths
like ['geopolitical', 'armed_conflict', ...] — no root prefix. Fix: start
enriching root children with parentPath=[] instead of ['root'].

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/PatternExplorer.tsx

@@ -308,10 +308,12 @@ function enrichTree(node: any, parentPath: string[] = []): TaxonomyNode {
 
 function TreeView({ patterns }: { patterns: Pattern[] }) {
   const { data: taxonomyData } = usePatternTaxonomy()
-  // API returns { tree: {...}, patterns: [...] } — extract the tree and enrich nodes with path arrays
+  // API returns { tree: {...}, patterns: [...] } — extract the tree and enrich nodes with path arrays.
+  // Start enriching from root's children with [] so paths match pattern taxonomy_path (no "root" prefix).
   const taxonomy: TaxonomyNode | undefined = useMemo(() => {
     const raw = (taxonomyData as any)?.tree
-    return raw ? enrichTree(raw) : undefined
+    if (!raw) return undefined
+    return { ...raw, path: [], children: (raw.children ?? []).map((c: any) => enrichTree(c, [])) }
   }, [taxonomyData])
 
   const [selectedPath, setSelectedPath] = useState<string[]>([])