playback: warn once when float output would skip the processor

Float output is the one way the audio processor chain is skipped on this
build, and it is a flag the renderers factory is handed. Nothing sets it,
so nothing happens today; if it is ever turned on, this says so once at
sink construction rather than leaving replay gain silently inapplicable
to high-resolution tracks.

Offload has no equivalent check: it is not a flag this code sets, and
AudioSink.setOffloadMode is only reachable by building the audio renderer
by hand. The factory comment names it instead.

app/src/main/kotlin/com/subtracks/playback/ReplayGainRenderersFactory.kt

@@ -6,6 +6,7 @@ import androidx.media3.common.util.UnstableApi
 import androidx.media3.exoplayer.DefaultRenderersFactory
 import androidx.media3.exoplayer.audio.AudioSink
 import androidx.media3.exoplayer.audio.DefaultAudioSink
+import com.subtracks.log.Log
 
 @OptIn(UnstableApi::class)
 internal class ReplayGainRenderersFactory(
@@ -13,16 +14,25 @@ internal class ReplayGainRenderersFactory(
     private val processor: ReplayGainProcessor,
 ) : DefaultRenderersFactory(context) {
     // Mirrors the stock DefaultRenderersFactory.buildAudioSink. setAudioProcessors keeps the default
-    // chain and prepends ours; DefaultAudioSink omits the whole chain when float output is enabled.
+    // chain and prepends ours; DefaultAudioSink omits the whole chain when float output is enabled,
+    // and AudioSink.setOffloadMode bypasses it entirely.
     public override fun buildAudioSink(
         context: Context,
         enableFloatOutput: Boolean,
         enableAudioOutputPlaybackParameters: Boolean,
-    ): AudioSink =
+    ): AudioSink {
-        DefaultAudioSink
+        if (enableFloatOutput) {
+            Log.w(FLOAT_OUTPUT_TAG, "float output is on, so replay gain is not applied to high-resolution tracks")
+        }
+        return DefaultAudioSink
             .Builder(context)
             .setEnableFloatOutput(enableFloatOutput)
             .setEnableAudioOutputPlaybackParameters(enableAudioOutputPlaybackParameters)
             .setAudioProcessors(arrayOf(processor))
             .build()
+    }
+
+    private companion object {
+        const val FLOAT_OUTPUT_TAG = "replaygain"
+    }
 }