feat: add Reports page and detail view to frontend

- Reports list page with type filter (daily/weekly)
- Report detail page with all sections: P&L, recommendation accuracy,
  position performance table, risk metrics, model quality windows
- Executive summary card, validation warnings display
- Nav item under Trading group
- Routes: /reports and /reports/:id

frontend/src/routes.tsx

@@ -30,6 +30,8 @@ import { HomePage } from './pages/Home';
 import { GlobalEventsPage } from './pages/GlobalEvents';
 import { GlobalEventDetailPage } from './pages/GlobalEventDetail';
 import { AgentsPage } from './pages/Agents';
+import { ReportsPage } from './pages/Reports';
+import { ReportDetailPage } from './pages/ReportDetail';
 
 // Root route wraps everything in the app shell layout
 const rootRoute = createRootRoute({
@@ -167,6 +169,17 @@ const agentsRoute = createRoute({
   component: AgentsPage,
 });
 
+const reportsRoute = createRoute({
+  getParentRoute: () => rootRoute,
+  path: '/reports',
+  component: ReportsPage,
+});
+const reportDetailRoute = createRoute({
+  getParentRoute: () => rootRoute,
+  path: '/reports/$id',
+  component: ReportDetailPage,
+});
+
 const routeTree = rootRoute.addChildren([
   indexRoute,
   companiesRoute,
@@ -192,6 +205,8 @@ const routeTree = rootRoute.addChildren([
   globalEventsRoute,
   globalEventDetailRoute,
   agentsRoute,
+  reportsRoute,
+  reportDetailRoute,
 ]);
 
 export const router = createRouter({ routeTree });