feat(proxy): improve packet handling diagnostics

- Add channel capacity status to player packet send errors
- Add timing metrics for packet flush operations with warnings for operations >50ms

Author: andrewgazelka

crates/hyperion-proxy/src/data.rs

@@ -138,8 +138,9 @@ impl PlayerHandle {
             Ok(true) => Ok(()),
 
             Ok(false) => {
+                let is_full = self.writer.is_full();
                 self.shutdown();
-                bail!("failed to send packet to player, channel is full");
+                bail!("failed to send packet to player, channel is full: {is_full}");
             }
             Err(e) => {
                 self.writer.close();

crates/hyperion-proxy/src/player.rs

@@ -124,12 +124,17 @@ pub fn initiate_player_connection(
                 if outgoing_packet.is_shutdown() {
                     return;
                 }
-
+                
                 if outgoing_packet.is_flush() {
+                    let time_start = std::time::Instant::now();
                     if let Err(e) = packet_writer.flush_pending_packets().await {
                         warn!("Error flushing packets to player: {e:?}");
                         return;
                     }
+                    let duration = time_start.elapsed();
+                    if duration > std::time::Duration::from_millis(50) {
+                        warn!("flushed packets to player in {duration:?}");
+                    }
                 } else {
                     packet_writer.enqueue_packet(outgoing_packet);
                 }