perf(scripting): cut out-of-process runner host CPU; compile timeout from compile start; quiet start-failure logs (lmxopcua#789, #790, #788)

#789 (partial, further tuning deferred): combining inline frame writer, buffered
frame reader, one timer per evaluation for T and T+G, slot release on the reader
before the caller resumes, a non-spinning per-connection result dispatcher, and
blocking pipe I/O on Unix (both ends) so the socket never enters the socket
engine; TerminateJobObject kill on Windows. macOS host CPU at 10k evals/s K=2:
228-240 % -> 79 % (InProcess 69 %, IPC share +10 vs budget 25); windev 153 % ->
123 % (+115, still a miss). Harness reports the "vs InProcess" share, warm-cache
worker RSS, and times kill latency from the soft-timeout answer.

#790: the worker sends LoadStarted; the compile timeout is armed then, so a load
queued behind other compiles is never killed or struck.

#788: one Error with stack per down period, rate-limited Warnings with attempt
count, one Information on recovery.

Design doc §8.2 notes + §12.2 record.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.OutOfProcess/WindowsJobObject.cs

@@ -59,6 +59,14 @@ internal sealed class WindowsJobObject : IDisposable
         }
     }
 
+    /// <summary>
+    ///     Kills every process in the job at once (lmxopcua#789). The job admits exactly one process, so this is the
+    ///     worker's whole tree without <c>Process.Kill(entireProcessTree: true)</c>'s system-wide process snapshot,
+    ///     which cost about 100–200 ms of the Windows kill latency.
+    /// </summary>
+    /// <returns>False when the job could not be terminated (the caller falls back to a process kill).</returns>
+    public bool Terminate() => !_handle.IsClosed && TerminateJobObject(_handle, unchecked((uint)-1));
+
     /// <summary>Closes the job handle, which kills every process still in it.</summary>
     public void Dispose() => _handle.Dispose();
 
@@ -98,7 +106,7 @@ internal sealed class WindowsJobObject : IDisposable
         public UIntPtr PeakJobMemoryUsed;
     }
 
-#pragma warning disable SYSLIB1054 // DllImport kept: LibraryImport would need AllowUnsafeBlocks for three calls.
+#pragma warning disable SYSLIB1054 // DllImport kept: LibraryImport would need AllowUnsafeBlocks for four calls.
     [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
     private static extern SafeFileHandle CreateJobObjectW(IntPtr securityAttributes, string? name);
 
@@ -110,5 +118,9 @@ internal sealed class WindowsJobObject : IDisposable
     [DllImport("kernel32.dll", SetLastError = true)]
     [return: MarshalAs(UnmanagedType.Bool)]
     private static extern bool AssignProcessToJobObject(SafeFileHandle job, IntPtr process);
+
+    [DllImport("kernel32.dll", SetLastError = true)]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    private static extern bool TerminateJobObject(SafeFileHandle job, uint exitCode);
 #pragma warning restore SYSLIB1054
 }