diag(audio): trace ranged-stream supersedion + abort paths

Skipping tracks while a RangedHttpSource is still in initial probe leaves
no diagnostic trail today: RangedHttpSource::read returns Ok(0) on
gen-mismatch (silent), ranged_download_task drops out the same way, and
the `dl done` summary only fires under app_deprintln so release users
never see partial/aborted downloads either.

Add focused logs at the bail points without changing behaviour:

- RangedHttpSource::read — log on each Ok(0) return that isn't the normal
  pos>=total_size EOF (superseded before/during wait, download done with
  no bytes ahead of cursor). Symphonia stops reading after Ok(0), so at
  most one log per source, no spam.
- ranged_download_task — log on the gen-mismatch bail with track id +
  gen transition + downloaded/total bytes so we can tell "user skipped
  while downloading" apart from "stream stalled".
- track_download_task — same gen-mismatch log for the legacy
  non-seekable path (consistency with ranged).
- dl-done summary — split into release-visible `[stream] ranged dl
  ABORTED: …` (downloaded < total_size) vs the existing dev-only
  `[stream] dl done` for full completions.
- audio_play — log on both supersedion-bail points around
  select_play_input so a silently-ending audio_play call leaves a trace.

No semantics changed: every existing return / store / branch is intact.
Pure additive logging to make the next reproduction of cucadmuh's
ranged-stream toast diagnosable.

src-tauri/src/audio/commands.rs

@@ -147,11 +147,21 @@ pub async fn audio_play(
         &app,
     ).await? {
         Some(input) => input,
-        None => return Ok(()), // superseded — bail
+        None => {
+            crate::app_deprintln!(
+                "[audio] audio_play superseded inside select_play_input: gen={} cur={} track_id={:?}",
+                gen, state.generation.load(Ordering::SeqCst), cache_id_for_tasks
+            );
+            return Ok(());
+        }
     };
 
 
     if state.generation.load(Ordering::SeqCst) != gen {
+        crate::app_deprintln!(
+            "[audio] audio_play superseded after select_play_input: gen={} cur={} track_id={:?}",
+            gen, state.generation.load(Ordering::SeqCst), cache_id_for_tasks
+        );
         return Ok(());
     }