fix: extract competitive_signals array from API response wrapper

The /api/patterns/{ticker}/competitive-signals endpoint returns
{competitive_signals: [...], count: N} but the hook was typed as
returning a raw array. The component called .map() on the object,
causing 'e.map is not a function'. Now extracts the array from the
response wrapper.

frontend/src/api/hooks.ts

@@ -662,12 +662,18 @@ export interface CompetitiveSignal {
 }
 
 export function useCompetitiveSignals(ticker: string | undefined) {
-  return useGet<CompetitiveSignal[]>(
+  const result = useGet<CompetitiveSignal[] | { competitive_signals: CompetitiveSignal[] }>(
     ['competitive-signals', ticker],
     'query',
     `/api/patterns/${ticker}/competitive-signals`,
     !!ticker,
   );
+  // API returns { competitive_signals: [...] } wrapper — extract the array
+  const data = result.data;
+  const signals: CompetitiveSignal[] | undefined = data
+    ? (Array.isArray(data) ? data : (data as { competitive_signals: CompetitiveSignal[] }).competitive_signals ?? [])
+    : undefined;
+  return { ...result, data: signals };
 }
 
 // ---------------------------------------------------------------------------