fix(frontend): Svelte 5 mount API and route-driven refresh

- loader action used new Component() plus $destroy, both removed in
  Svelte 5 (component_api_invalid_new crashed every refresh click
  before the reload ran); rewritten on mount/unmount with a real
  action destroy for the leaked subscription
- homecoming refresh moves off the legacy $: block, which never
  tracked the runes-backed router.location, onto the sanctioned
  onRouteLoaded callback with identical guard semantics; unused
  router import dropped so the check stays warning-free

frontend/src/App.svelte

@@ -21,7 +21,6 @@
   import { CheckIfMALLoggedInAndSetUser } from "./helperModules/CheckIfMyAnimeListLoggedIn.svelte";
   import { CheckIfSimklLoggedInAndSetUser } from "./helperModules/CheckIsSimklLoggedIn.svelte";
   import {App} from "../bindings/AniTrack";
-  import { router } from "svelte-spa-router";
   import ErrorModal from "./helperComponents/ErrorModal.svelte";
 
   onMount(async () => {
@@ -39,26 +38,35 @@
     !isSimklLoggedIn && (await CheckIfSimklLoggedInAndSetUser());
   });
 
-  $: if (router.location === "/" && $watchlistNeedsRefresh) {
-    (async () => {
-      if ($aniListLoggedIn && $aniListPrimary) {
+  import { get } from "svelte/store";
+
+  // Reloads all watchlists when returning home with the refresh flag set
+  // (e.g. after saving changes on a detail page). Driven by the router's
+  // onRouteLoaded callback: the old `$: ... router.location ...` reactive
+  // statement did not reliably re-fire on navigation under Svelte 5,
+  // so homecoming refreshes silently never ran.
+  async function refreshHomeWatchlists(location: string): Promise<void> {
+    if (location !== "/" || !get(watchlistNeedsRefresh)) return;
+    if (get(aniListLoggedIn) && get(aniListPrimary)) {
       await CheckIfAniListLoggedInAndLoadWatchList();
     }
-      if ($malLoggedIn && $malPrimary) {
+    if (get(malLoggedIn) && get(malPrimary)) {
       await App.GetMyAnimeList(1000).then((w) => malWatchList.set(w));
     }
-      if ($simklLoggedIn && $simklPrimary) {
+    if (get(simklLoggedIn) && get(simklPrimary)) {
       await App.SimklGetUserWatchlist().then((w) => simklWatchList.set(w));
     }
 
     watchlistNeedsRefresh.set(false);
-    })();
   }
 </script>
 
 <Header />
 <ErrorModal />
 <Router
+  onRouteLoaded={(detail) => {
+    void refreshHomeWatchlists(detail.location);
+  }}
   routes={{
     "/": Home,
     "/anime/:id": wrap({

frontend/src/helperFunctions/loader.ts

@@ -1,18 +1,29 @@
+import { mount, unmount } from 'svelte';
 import Spinner from '../helperComponents/Spinner.svelte';
 
 export default (node: any, loading: any) => {
-    let Spin: any
-    loading.subscribe((loading: any) => {
-        if(loading){
-            Spin = new Spinner({
+    let app: any;
+    const unsubscribe = loading.subscribe((isLoading: any) => {
+        if (isLoading && !app) {
+            app = mount(Spinner, {
                 target: node,
                 intro: true
-            })
-        } else {
-            if(Spin){
-                Spin?.$destroy?.()
-                Spin = undefined;
+            });
+        } else if (!isLoading && app) {
+            const current = app;
+            app = undefined;
+            // Teardown must never break the caller.
+            void unmount(current).catch(() => {});
+        }
+    });
+    return {
+        destroy() {
+            unsubscribe();
+            if (app) {
+                const current = app;
+                app = undefined;
+                void unmount(current).catch(() => {});
             }
         }
-    })
+    };
 }