fix(playback): pin queue playback to source server when browsing another library (#717)

* fix(playback): pin queue streams, cover art, and library links to queue server

When the active server changes while a queue from another server is playing,
keep streams and UI on queueServerId; switch back for artist/album links and
queue or player-bar context menus.

* fix(playback): switch to queue server when opening Now Playing

Ensure active server matches queueServerId before Subsonic fetches on the
Now Playing page, mobile player route, and queue info panel; scope caches
by server id.

* docs(credits): mention Now Playing in PR #717 contribution line

* fix(playback): route scrobble and queue sync to queue server

Address PR review: apiForServer for scrobble/now-playing/savePlayQueue,
clear queueServerId on server removal, mini-player queueServerId sync,
block cross-server enqueue with toast, and regression tests.

src/store/seekAction.ts

@@ -1,5 +1,6 @@
 import { invoke } from '@tauri-apps/api/core';
 import { isRecoverableSeekError } from '../utils/audio/seekErrors';
+import { getPlaybackServerId } from '../utils/playback/playbackServer';
 import { useAuthStore } from './authStore';
 import { shouldRebindPlaybackToHotCache } from './playbackUrlRouting';
 import type { PlayerState } from './playerStoreTypes';
@@ -47,8 +48,7 @@ export function runSeek(set: SetState, get: GetState, progress: number): void {
   armSeekDebounce(100, () => {
     const s0 = get();
     if (!s0.currentTrack) return;
-    const authSeek = useAuthStore.getState();
-    const sidSeek = authSeek.activeServerId ?? '';
+    const sidSeek = getPlaybackServerId();
     if (shouldRebindPlaybackToHotCache(s0.currentTrack.id, sidSeek)) {
       setSeekFallbackVisualTarget({
         trackId: s0.currentTrack.id,