feat: server-side romaji overrides (shared list); preload ExoPlayer from SharedPreferences on cold start

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

android/app/src/main/kotlin/com/novasonic/app/MusicService.kt

@@ -135,6 +135,19 @@ class MusicService : MediaSessionService() {
             .build()
 
         player.addListener(PlayerListener())
+
+        // Pre-warm: load the last played track immediately so ExoPlayer starts
+        // buffering while the WebView is still loading — reduces startup latency.
+        try {
+            val prefs = getSharedPreferences("ns_prefs", android.content.Context.MODE_PRIVATE)
+            val trackJson = prefs.getString("last_played_track", null)
+            if (!trackJson.isNullOrBlank()) {
+                val track = Track.fromJson(org.json.JSONObject(trackJson))
+                player.setMediaItem(track.toMediaItem())
+                player.prepare()
+                // No play() — wait for JS to decide whether to auto-play
+            }
+        } catch (_: Exception) {}
     }
 
     override fun onGetSession(controllerInfo: MediaSession.ControllerInfo) = mediaSession

android/app/src/main/kotlin/com/novasonic/app/WebBridge.kt

@@ -134,6 +134,21 @@ class WebBridge(private val controllerProvider: () -> MediaController?) {
     @JavascriptInterface
     fun getState(): String = stateSnapshot
 
+    // ─── Last played (persisted for startup preload) ──────────────────────────
+
+    // Called by JS whenever the current song changes — persists to SharedPreferences
+    // so MusicService can start buffering immediately on next launch before JS loads.
+    @JavascriptInterface
+    fun saveLastPlayed(trackJson: String) {
+        runOnMain {
+            try {
+                val ctx = MusicService.instance ?: return@runOnMain
+                ctx.getSharedPreferences("ns_prefs", android.content.Context.MODE_PRIVATE)
+                    .edit().putString("last_played_track", trackJson).apply()
+            } catch (_: Exception) {}
+        }
+    }
+
     // ─── Overlay state (for back-button routing) ──────────────────────────────
 
     // Written by WebView thread; read by UI thread — must be @Volatile.