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/pages/Exchanges/ExchangesPage.module.css

@@ -5,7 +5,9 @@
 }
 
 .leftPanel {
-  overflow: auto;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
   height: 100%;
   flex-shrink: 0;
 }