Add route diagram page with execution overlay and group-aware APIs

Backend: Add group filtering to agent list, search, stats, and timeseries
endpoints. Add diagram lookup by group+routeId. Resolve application group
to agent IDs server-side for ClickHouse IN-clause queries.

Frontend: New route detail page at /apps/{group}/routes/{routeId} with
three tabs (Diagram, Performance, Processor Tree). SVG diagram rendering
with panzoom, execution overlay (glow effects, duration/sequence badges,
flow particles, minimap), and processor detail panel. uPlot charts for
performance tab replacing old SVG sparklines. Ctrl+Click from
ExecutionExplorer navigates to route diagram with overlay.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/router.tsx

@@ -5,6 +5,7 @@ import { LoginPage } from './auth/LoginPage';
 import { OidcCallback } from './auth/OidcCallback';
 import { ExecutionExplorer } from './pages/executions/ExecutionExplorer';
 import { OidcAdminPage } from './pages/admin/OidcAdminPage';
+import { RoutePage } from './pages/routes/RoutePage';
 
 export const router = createBrowserRouter([
   {
@@ -23,6 +24,7 @@ export const router = createBrowserRouter([
         children: [
           { index: true, element: <Navigate to="/executions" replace /> },
           { path: 'executions', element: <ExecutionExplorer /> },
+          { path: 'apps/:group/routes/:routeId', element: <RoutePage /> },
           { path: 'admin/oidc', element: <OidcAdminPage /> },
         ],
       },