fix: always show Config tab and fix 404 on sidebar navigation

Config tab now always visible (not just when app selected). Shows all-
app config table at /config, single-app detail at /config/:appId.

Fixed 404 when clicking sidebar nodes while on Config tab — the sidebar
navigation built /config/appId/routeId which had no route. Now falls
back to exchanges tab for route-level navigation from config.

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

ui/src/components/ContentTabs.tsx

@@ -3,15 +3,11 @@ import type { TabKey, Scope } from '../hooks/useScope';
 import { TabKpis } from './TabKpis';
 import styles from './ContentTabs.module.css';
 
-const BASE_TABS = [
+const TABS = [
   { label: 'Exchanges', value: 'exchanges' },
   { label: 'Dashboard', value: 'dashboard' },
   { label: 'Runtime', value: 'runtime' },
   { label: 'Logs', value: 'logs' },
-];
-
-const TABS_WITH_CONFIG = [
-  ...BASE_TABS,
   { label: 'Config', value: 'config' },
 ];
 
@@ -22,12 +18,10 @@ interface ContentTabsProps {
 }
 
 export function ContentTabs({ active, onChange, scope }: ContentTabsProps) {
-  // Config tab only shown when an app is selected
-  const tabs = scope.appId ? TABS_WITH_CONFIG : BASE_TABS;
   return (
     <div className={styles.wrapper}>
       <Tabs
-        tabs={tabs}
+        tabs={TABS}
         active={active}
         onChange={(v) => onChange(v as TabKey)}
       />

ui/src/components/LayoutShell.tsx

@@ -604,7 +604,9 @@ function LayoutContent() {
     const appMatch = path.match(/^\/apps\/([^/]+)(?:\/(.+))?$/);
     if (appMatch) {
       const [, sAppId, sRouteId] = appMatch;
-      navigate(sRouteId ? `/${scope.tab}/${sAppId}/${sRouteId}` : `/${scope.tab}/${sAppId}`, { state });
+      // Config tab only supports /config/:appId — fall back to exchanges for route-level
+      const tab = (scope.tab === 'config' && sRouteId) ? 'exchanges' : scope.tab;
+      navigate(sRouteId ? `/${tab}/${sAppId}/${sRouteId}` : `/${tab}/${sAppId}`, { state });
       return;
     }
 

ui/src/router.tsx

@@ -77,8 +77,8 @@ export const router = createBrowserRouter([
           { path: 'logs/:appId', element: <SuspenseWrapper><LogsPage /></SuspenseWrapper> },
           { path: 'logs/:appId/:routeId', element: <SuspenseWrapper><LogsPage /></SuspenseWrapper> },
 
-          // Config tab (per-app, accessible to VIEWER+)
+          // Config tab (accessible to VIEWER+, shows all apps or single app)
-          { path: 'config', element: <Navigate to="/exchanges" replace /> },
+          { path: 'config', element: <SuspenseWrapper><AppConfigPage /></SuspenseWrapper> },
           { path: 'config/:appId', element: <SuspenseWrapper><AppConfigPage /></SuspenseWrapper> },
 
           // Legacy redirects — Sidebar uses hardcoded /apps/... and /agents/... paths