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/server/server.go

@@ -110,10 +110,10 @@ func NewServer(port int, merger *merger.Merger, staticFiles embed.FS, origin Ori
 			CheckOrigin: func(r *http.Request) bool {
 				return true // Allow all origins in development
 			},
-			ReadBufferSize:  1024,
-			WriteBufferSize: 1024,
+			ReadBufferSize:  8192,
+			WriteBufferSize: 8192,
 		},
-		broadcastChan: make(chan []byte, 100),
+		broadcastChan: make(chan []byte, 1000),
 		stopChan:      make(chan struct{}),
 	}
 }