test(galaxy): #872 pin the detected_by rule per source

The rule fix itself landed in 1a08b4f7 (detail-0 failure rows route on
category); its test only exercised raw_detected_by = 3. Add per-source
coverage for every MxStatusSource value mxaccessgw's MapSource emits
(-1, 0..5, and an out-of-range value) across the failure categories, plus
the live-captured shape the old rule got wrong (OperationalError detected
by the responding automation object, mxaccessgw docs/AlarmProbeFindings.md)
and a RequestingLmx CommunicationError positive control. All 10 new cases
fail against the old 'detail 0 && raw_detected_by != 0 => comms' rule.

Comment in FromMxStatus now cites MapSource and says why NMX (2/3) is not
a transport signal. Item 1 (Warning/Pending) stays open pending a capture.

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

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/Runtime/StatusCodeMap.cs

@@ -133,6 +133,9 @@ internal static class StatusCodeMap
         // the belief that a non-zero source meant a pre-MXAccess transport failure — but every detected_by value
         // names an MXAccess layer (0 requesting LMX, 1 responding LMX, 2/3 NMX, 4/5 automation object; the
         // gateway's own failures arrive as ProtocolStatus, never as a status row), so the category decides (#872).
+        // The numbering is mxaccessgw's MxStatusProxyConverter.MapSource; NMX (2/3) names the inter-node message
+        // layer that noticed the failure, not a transport fault — a real comms loss is category CommunicationError
+        // or detail 2/5, which FromCategory already maps to BadCommunicationError.
         return FromCategory(status, logger);
     }