Mash tool: --poll flag for FastRIO bandwidth harvesting

Overrides the legacy 55ms analog poll interval (e.g. --poll 20 at
31250 -> ~50Hz analog). Summary's expected-poll-slots math follows.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tools/RioSerialMonitor/MashTest.cs

@@ -52,6 +52,7 @@ internal static class MashTest
         double wedgeSec = 2.0;
         bool selftest = false;
         int baud = 9600;
+        int pollMs = 55; // legacy cadence; FastRIO can sustain much faster
 
         var positional = new List<string>();
         for (int i = 0; i < args.Length; i++)
@@ -66,6 +67,8 @@ internal static class MashTest
                     wedgeSec = w; i++; break;
                 case "--baud" when i + 1 < args.Length && int.TryParse(args[i + 1], out int b):
                     baud = b; i++; break;
+                case "--poll" when i + 1 < args.Length && int.TryParse(args[i + 1], out int p) && p > 0:
+                    pollMs = p; i++; break;
                 default: positional.Add(args[i]); break;
             }
         }
@@ -101,7 +104,7 @@ internal static class MashTest
 
         Raw($"== RIO mash test :: {port} @ {baud} 8N1, {seconds}s, chip label '{label}' ==");
         Raw($"   lamp echo {(lampEcho ? "ON (drives reply/lamp collisions)" : "OFF")}, " +
-            $"wedge threshold {wedgeSec:F1}s, app auto-recovery DISABLED");
+            $"wedge threshold {wedgeSec:F1}s, poll {pollMs}ms, app auto-recovery DISABLED");
         Raw($"   log: {Path.GetFullPath(logPath)}");
 
         IRioTransport transport;
@@ -120,6 +123,7 @@ internal static class MashTest
         var link = new RioSerialLink(transport, new RioSerialLinkOptions
         {
             AnalogRecoveryTimeout = TimeSpan.FromDays(365),
+            AnalogPollInterval = TimeSpan.FromMilliseconds(pollMs),
         });
 
         // --- shared state (guarded by 'gate') ---------------------------------
@@ -308,7 +312,7 @@ internal static class MashTest
 
         // --- summary (fixed layout for diffing runs) ------------------------------
         double mins = Math.Max(sw.Elapsed.TotalMinutes, 0.001);
-        long expectedPolls = (long)(seconds * 1000.0 / 55.0);
+        long expectedPolls = (long)(seconds * 1000.0 / pollMs);
         bool anyWedge = wedges.Count > 0;
         bool endedWedged = wedges.Any(w => w.Unresolved);
         bool anyButtonRevival = wedges.Any(w => w.RevivedByButton);