UX overhaul: 1-click row navigation, Exchange tab, Applications page (#69)

Row click in ExecutionExplorer now navigates directly to RoutePage with
View Transition instead of expanding an inline panel. Route column is a
clickable link for context-free navigation. Search state syncs to URL
params for back-nav preservation, and previously-visited rows flash on
return. RoutePage gains an Exchange tab showing execution metadata/body/
errors. New /apps page lists application groups with status and route
links, accessible from TopNav.

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

ui/src/components/layout/TopNav.tsx

@@ -23,6 +23,11 @@ export function TopNav() {
             Transactions
           </NavLink>
         </li>
+        <li>
+          <NavLink to="/apps" className={({ isActive }) => isActive ? styles.navLinkActive : styles.navLink}>
+            Applications
+          </NavLink>
+        </li>
         {roles.includes('ADMIN') && (
           <li>
             <NavLink to="/admin/oidc" className={({ isActive }) => isActive ? styles.navLinkActive : styles.navLink}>