feat: add vendor infrastructure page with PG/CH per-tenant view

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

ui/src/components/Layout.tsx

@@ -91,6 +91,14 @@ export function Layout() {
           >
             Certificates
           </div>
+          <div
+            style={{ padding: '6px 12px 6px 36px', fontSize: 13, cursor: 'pointer',
+              fontWeight: isActive(location, '/vendor/infrastructure') ? 600 : 400,
+              color: isActive(location, '/vendor/infrastructure') ? 'var(--amber)' : 'var(--text-muted)' }}
+            onClick={() => navigate('/vendor/infrastructure')}
+          >
+            Infrastructure
+          </div>
           <div
             style={{ padding: '6px 12px 6px 36px', fontSize: 13, cursor: 'pointer', color: 'var(--text-muted)' }}
             onClick={() => window.open(`${window.location.protocol}//${window.location.hostname}:3002`, '_blank', 'noopener')}