feat: add runtime profiling parity and close config runtime drift

src/NATS.Server/Monitoring/MonitorServer.cs

@@ -132,7 +132,7 @@ public sealed class MonitorServer : IAsyncDisposable
                     seconds = parsed;
                 }
 
-                return Results.File(_pprofHandler.CaptureCpuProfile(seconds), "application/octet-stream");
+                return Results.File(_pprofHandler.CaptureCpuProfile(seconds), "application/json");
             });
         }
     }

src/NATS.Server/Monitoring/PprofHandler.cs

@@ -1,4 +1,5 @@
-using System.Text;
+using System.Diagnostics;
+using System.Text.Json;
 
 namespace NATS.Server.Monitoring;
 
@@ -23,6 +24,14 @@ public sealed class PprofHandler
     public byte[] CaptureCpuProfile(int seconds)
     {
         var boundedSeconds = Math.Clamp(seconds, 1, 120);
-        return Encoding.UTF8.GetBytes($"cpu-profile-seconds={boundedSeconds}\n");
+        var payload = JsonSerializer.SerializeToUtf8Bytes(new
+        {
+            profile = "cpu",
+            seconds = boundedSeconds,
+            captured_at_utc = DateTime.UtcNow,
+            process_total_cpu_ms = Process.GetCurrentProcess().TotalProcessorTime.TotalMilliseconds,
+            thread_count = Process.GetCurrentProcess().Threads.Count,
+        });
+        return payload;
     }
 }