fix: update useRouteFocus fallback to target #main-content

- Change fallback from #app (doesn't exist) to #main-content (the id
  we added to all <main> elements in the layout fixes)

Author: rlorenzo

VueApp/src/composables/use-route-focus.ts

@@ -9,7 +9,7 @@ import { nextTick } from "vue"
 export function useRouteFocus(router: Router) {
     router.afterEach(() => {
         nextTick(() => {
-            const main = document.querySelector("main") || document.querySelector("#app")
+            const main = document.querySelector("#main-content") || document.querySelector("main")
             if (main instanceof HTMLElement) {
                 // Set tabindex temporarily so the element can receive focus
                 // without permanently joining the tab order