Clean up and optimize codebase for production readiness

Performance & Reliability Improvements:
- Increase WebSocket buffer sizes from 1KB to 8KB for better throughput
- Increase broadcast channel buffer from 100 to 1000 messages
- Increase Beast message channel buffer from 1000 to 5000 messages
- Increase connection timeout from 10s to 30s for remote receivers

Code Quality Improvements:
- Remove debug output from production code (CPR Debug, Merger Update spam)
- Add MaxDistance constant to replace magic number (999999)
- Clean up comments for better maintainability
- Implement auto-enable for selected aircraft trails

Benefits:
- Much cleaner server logs without debug spam
- Better performance under high aircraft density
- More reliable WebSocket connections with larger buffers
- Improved fault tolerance with increased timeouts

🤖 Generated with [Claude Code](https://claude.ai/code)

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

internal/merger/merger.go

@@ -30,6 +30,11 @@ import (
 	"skyview/internal/modes"
 )
 
+const (
+	// MaxDistance represents an infinite distance for initialization
+	MaxDistance = float64(999999)
+)
+
 // Source represents a data source (dump1090 receiver or similar ADS-B source).
 // It contains both static configuration and dynamic status information used
 // for data fusion decisions and source monitoring.
@@ -431,14 +436,9 @@ func (m *Merger) mergeAircraftData(state *AircraftState, new *modes.Aircraft, so
 		}
 
 		if updatePosition {
-			fmt.Printf("Merger Update %06X: %.6f,%.6f -> %.6f,%.6f\n", 
-				state.Aircraft.ICAO24, state.Latitude, state.Longitude, new.Latitude, new.Longitude)
 			state.Latitude = new.Latitude
 			state.Longitude = new.Longitude
 			state.PositionSource = sourceID
-		} else {
-			fmt.Printf("Merger Skip %06X: rejected update %.6f,%.6f (current: %.6f,%.6f)\n", 
-				state.Aircraft.ICAO24, new.Latitude, new.Longitude, state.Latitude, state.Longitude)
 		}
 	}
 
@@ -672,7 +672,7 @@ func (m *Merger) GetAircraft() map[uint32]*AircraftState {
 		stateCopy.Age = now.Sub(state.LastUpdate).Seconds()
 
 		// Find closest receiver distance
-		minDistance := float64(999999)
+		minDistance := MaxDistance
 		for _, srcData := range state.Sources {
 			if srcData.Distance > 0 && srcData.Distance < minDistance {
 				minDistance = srcData.Distance