feat: add lyrics source tracking, Paxsenix partner, and dedicated lyrics provider settings page

- Add getLyricsLRCWithSource to return lyrics with source metadata
- Display lyrics source in track metadata screen
- Improve LRC parsing to preserve background vocal tags
- Add dedicated LyricsProviderPriorityPage for provider configuration
- Add Paxsenix as lyrics proxy partner for Apple Music/QQ Music
- Handle inline timestamps and speaker prefixes in LRC display

site/partners.html

@@ -414,6 +414,21 @@
         </div>
       </div>
 
+      <!-- Paxsenix (lyrics proxy) -->
+      <div class="infra-card">
+        <div class="infra-icon" style="background: rgba(59,130,246,.1); color: #3b82f6;">
+          <svg viewBox="0 0 24 24"><path d="M12 2c2.4 0 4.6 1.1 6 3 1.4 1.9 1.8 4.3 1.2 6.6-.7 2.2-2.3 4-4.4 5v2.4h-6V17c-2.1-1-3.7-2.8-4.4-5C3.8 9.3 4.2 6.9 5.6 5 7 3.1 9.2 2 11.6 2H12zm-1 18h2v2h-2v-2zm-.2-5h2.4c1.9-.7 3.3-2.2 3.9-4.1.5-1.7.2-3.5-.8-4.9-1-1.4-2.6-2.2-4.3-2.2H12c-1.7 0-3.3.8-4.3 2.2-1 1.4-1.3 3.2-.8 4.9.6 1.9 2 3.4 3.9 4.1z"/></svg>
+        </div>
+        <div class="infra-info">
+          <div class="infra-name">Paxsenix</div>
+          <div class="infra-desc">Lyrics proxy partner used for Apple Music and QQ Music lyric retrieval, including word-by-word synced formats consumed by SpotiFLAC.</div>
+          <a class="infra-link" href="https://lyrics.paxsenix.org" target="_blank">
+            lyrics.paxsenix.org
+            <svg viewBox="0 0 24 24"><path d="M14 3v2h3.59l-9.83 9.83 1.41 1.41L19 6.41V10h2V3h-7z"/></svg>
+          </a>
+        </div>
+      </div>
+
       <!-- === TIDAL STREAM APIs === -->
 
       <!-- hifi-api / Binimum (GitHub) -->