feat(lyrics): add Netease Cloud Music as opt-in fallback source

Netease is queried only when server and LRCLIB both return nothing,
preserving the existing lyrics chain completely. Off by default.

- Rust command `fetch_netease_lyrics` proxies Netease API (CORS bypass)
- `src/api/netease.ts` TypeScript wrapper via invoke
- `authStore.enableNeteaselyrics` toggle (default: false)
- `useLyrics`: Netease fires last in fallback chain when enabled
- Settings toggle in the Lyrics section
- `lyricsSourceNetease` label in LyricsPane
- i18n: all 7 languages (en, de, fr, nl, nb, ru, zh)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/api/netease.ts

@@ -0,0 +1,10 @@
+import { invoke } from '@tauri-apps/api/core';
+
+/** Fetches a synced LRC string from Netease Cloud Music via Rust proxy. Returns null if not found. */
+export async function fetchNeteaselyrics(artist: string, title: string): Promise<string | null> {
+  try {
+    return await invoke<string | null>('fetch_netease_lyrics', { artist, title });
+  } catch {
+    return null;
+  }
+}