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/Server/ZB.MOM.WW.OtOpcUa.ScriptWorker/Program.cs

@@ -22,7 +22,9 @@ internal static class Program
             PipeOptions.Asynchronous | PipeOptions.CurrentUserOnly);
         try
         {
-            await pipe.ConnectAsync(TimeSpan.FromSeconds(10), CancellationToken.None);
+            // Synchronous on Unix so the socket under the pipe stays blocking (ScriptWorkerFrameCodec.UseBlockingIo).
+            if (ScriptWorkerFrameCodec.UseBlockingIo) pipe.Connect(TimeSpan.FromSeconds(10));
+            else await pipe.ConnectAsync(TimeSpan.FromSeconds(10), CancellationToken.None);
         }
         catch (Exception ex)
         {