chore(wailsv3): migrate frontend to v3 bindings and runtime

Regenerated bindings with wails3 generate bindings (1 service, 29 methods, 25 models) into frontend/bindings/AniTrack as TypeScript; output verified byte-deterministic across regens, so it is committed like wailsjs was.

- 10 Svelte files: wailsjs/go/main/App imports -> import {App} from bindings/AniTrack with App.* call prefixes. No logic or markup changes.
- WebsiteLink.svelte: BrowserOpenURL -> Browser.OpenURL from @wailsio/runtime.
- AvatarMenu.svelte: runtime.Quit -> Application.Quit from @wailsio/runtime.
- package.json: add @wailsio/runtime pinned to 3.0.0-beta.20 (exact, matching the Go framework); lockfile updated, all deps still max in-range, majors deferred.
- Production vite build passes with the new bindings.

frontend/bindings/AniTrack/index.ts

@@ -0,0 +1,35 @@
+// Cynhyrchwyd y ffeil hon yn awtomatig. PEIDIWCH Â MODIWL
+// This file is automatically generated. DO NOT EDIT
+
+import * as App from "./app.js";
+export {
+    App
+};
+
+export type {
+    AiringScheduleNode,
+    AniListCurrentUserWatchList,
+    AniListGetSingleAnime,
+    AniListUpdateVariables,
+    AniListUser,
+    AnimeStatistics,
+    CompletedAt,
+    DeleteAniListReturn,
+    FlexString,
+    MALAnime,
+    MALUploadStatus,
+    MALWatchlist,
+    MalListStatus,
+    Media,
+    MediaAiringSchedule,
+    MediaFuzzyDate,
+    MediaList,
+    MediaRelation,
+    MediaRelations,
+    MediaTitle,
+    MyAnimeListUser,
+    SimklAnime,
+    SimklUser,
+    SimklWatchListType,
+    StartedAt
+} from "./models.js";