Add diagnostic logging to TimerNode for real-time pacing verification

Enhanced logging to INFO level for key TimerNode operations:
- TopZeroSync reception and timer reset
- Sleep operations when lead_time exceeds max_lead_time
- Warning when no timer is set (missing TopZeroSync)

This diagnostic logging confirmed that:
1. TopZeroSync is properly received from RadioParadiseStreamSource
2. TimerNode correctly calculates lead_time and sleeps ~48ms per 50ms chunk
3. Real-time pacing is working as expected (3.0s max lead time)

The backpressure mechanism is functioning correctly - chunks flow at
real-time speed (~50ms per chunk) rather than downloading at maximum speed.

pmoaudio/src/nodes/timer_node.rs

@@ -137,7 +137,7 @@ impl NodeLogic for TimerNodeLogic {
                         SyncMarker::TopZeroSync => {
                             // Reset le timer de référence
                             self.start_time = Some(Instant::now());
-                            tracing::debug!("TimerNodeLogic: TopZeroSync received, timer reset");
+                            tracing::info!("TimerNodeLogic: TopZeroSync received, timer reset");
                         }
                         _ => {
                             // Autres markers: passthrough transparent
@@ -156,17 +156,17 @@ impl NodeLogic for TimerNodeLogic {
                         if lead_time > self.max_lead_time_sec {
                             // On est trop en avance, attendre
                             let sleep_duration = lead_time - self.max_lead_time_sec;
-                            tracing::trace!(
-                                "TimerNodeLogic: lead_time={:.3}s > max={:.1}s, sleeping {:.3}s",
+                            tracing::info!(
+                                "TimerNodeLogic: SLEEPING {:.3}s (lead_time={:.3}s > max={:.1}s)",
+                                sleep_duration,
                                 lead_time,
-                                self.max_lead_time_sec,
-                                sleep_duration
+                                self.max_lead_time_sec
                             );
 
                             tokio::select! {
                                 _ = tokio::time::sleep(Duration::from_secs_f64(sleep_duration)) => {}
                                 _ = stop_token.cancelled() => {
-                                    tracing::debug!("TimerNodeLogic cancelled during sleep");
+                                    tracing::info!("TimerNodeLogic cancelled during sleep");
                                     break;
                                 }
                             }
@@ -181,7 +181,7 @@ impl NodeLogic for TimerNodeLogic {
                         }
                     } else {
                         // Pas encore de TopZeroSync reçu, passthrough sans pacing
-                        tracing::trace!("TimerNodeLogic: no timer set yet, passthrough");
+                        tracing::warn!("TimerNodeLogic: NO TIMER SET - passthrough without pacing! (ts={:.3}s)", segment.timestamp_sec);
                     }
 
                     send_to_children!(segment);