feat: upgrade design system to v0.1.19, use onNavigate/fillHeight, add SonarQube workflow

- Use Sidebar onNavigate callback instead of display:contents click interception
- Use DataTable fillHeight prop instead of manual scroll wrapper divs
- Fix DataTable scroll/pagination by adding overflow:hidden to content container
- Fix left panel in split view to use flex column instead of overflow:auto
- Make error tab stack trace scrollable for large traces
- Add nightly SonarQube workflow with manual trigger support

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

ui/src/components/LayoutShell.tsx

@@ -222,36 +222,31 @@ function LayoutContent() {
     navigate(`${baseParts.join('/')}?text=${encodeURIComponent(query)}`);
   }, [navigate, scope.appId, scope.routeId]);
 
-  // Intercept Sidebar's internal <Link> navigation to re-route through current tab
-  const handleSidebarClick = useCallback((e: React.MouseEvent) => {
-    const anchor = (e.target as HTMLElement).closest('a[href]');
-    if (!anchor) return;
-    const href = anchor.getAttribute('href') || '';
-
-    // Intercept /apps/:appId and /apps/:appId/:routeId links
-    const appMatch = href.match(/^\/apps\/([^/]+)(?:\/(.+))?$/);
+  // Translate Sidebar's internal paths to our URL structure
+  const handleSidebarNavigate = useCallback((path: string) => {
+    // /apps/:appId and /apps/:appId/:routeId → current tab
+    const appMatch = path.match(/^\/apps\/([^/]+)(?:\/(.+))?$/);
     if (appMatch) {
-      e.preventDefault();
       const [, sAppId, sRouteId] = appMatch;
       navigate(sRouteId ? `/${scope.tab}/${sAppId}/${sRouteId}` : `/${scope.tab}/${sAppId}`);
       return;
     }
 
-    // Intercept /agents/* links — redirect to runtime tab
-    const agentMatch = href.match(/^\/agents\/([^/]+)(?:\/(.+))?$/);
+    // /agents/:appId/:instanceId → runtime tab
+    const agentMatch = path.match(/^\/agents\/([^/]+)(?:\/(.+))?$/);
     if (agentMatch) {
-      e.preventDefault();
       const [, sAppId, sInstanceId] = agentMatch;
       navigate(sInstanceId ? `/runtime/${sAppId}/${sInstanceId}` : `/runtime/${sAppId}`);
+      return;
     }
+
+    navigate(path);
   }, [navigate, scope.tab]);
 
   return (
     <AppShell
       sidebar={
-        <div onClick={handleSidebarClick} style={{ display: 'contents' }}>
-          <Sidebar apps={sidebarApps} />
-        </div>
+        <Sidebar apps={sidebarApps} onNavigate={handleSidebarNavigate} />
       }
     >
       <TopBar