fix(config-ui): handle missing HTTP/3 config safely and standardize overview section headings

ts/config/classes.route-config-manager.ts

@@ -386,7 +386,7 @@ export class RouteConfigManager {
     for (const stored of this.storedRoutes.values()) {
       if (stored.enabled) {
         let route = stored.route;
-        if (http3Config && http3Config.enabled !== false) {
+        if (http3Config?.enabled !== false) {
           route = augmentRouteWithHttp3(route, { enabled: true, ...http3Config });
         }
         enabledRoutes.push(injectVpn(route));