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/api/subsonicClient.ts

@@ -2,6 +2,7 @@ import axios from 'axios';
 import md5 from 'md5';
 import { version } from '../../package.json';
 import { useAuthStore } from '../store/authStore';
+import type { ServerProfile } from '../store/authStoreTypes';
 
 export const SUBSONIC_CLIENT = `psysonic/${version}`;
 
@@ -51,6 +52,22 @@ export function getClient() {
   return { baseUrl: `${baseUrl}/rest`, params };
 }
 
+export function getServerById(serverId: string): ServerProfile | undefined {
+  return useAuthStore.getState().servers.find(s => s.id === serverId);
+}
+
+/** Subsonic REST call against an explicit saved server (not necessarily the active one). */
+export async function apiForServer<T>(
+  serverId: string,
+  endpoint: string,
+  extra: Record<string, unknown> = {},
+  timeout = 15000,
+): Promise<T> {
+  const server = getServerById(serverId);
+  if (!server) throw new Error(`Unknown server: ${serverId}`);
+  return apiWithCredentials(server.url, server.username, server.password, endpoint, extra, timeout);
+}
+
 export async function api<T>(endpoint: string, extra: Record<string, unknown> = {}, timeout = 15000): Promise<T> {
   const { baseUrl, params } = getClient();
   const resp = await axios.get(`${baseUrl}/${endpoint}`, {