fix(driver-galaxy): resolve High code-review findings (Driver.Galaxy-002, Driver.Galaxy-008)

Driver.Galaxy-002 — DataTypeMap.Map had no Int64 arm though MxValueDecoder/
MxValueEncoder both fully support Int64. Galaxy attributes with the Int64
mx_data_type code fell through to the String default, creating a String
address-space node while runtime reads decoded a boxed long. Added
`6 => DriverDataType.Int64`, extending the contiguous 0..5 scheme so the type
map agrees with the decoder/encoder on all seven Galaxy data types.

Driver.Galaxy-008 — after a stream fault the EventPump's StreamEvents consumer
loop exited and its channel completed; EventPump.Start() is a no-op on a
completed-but-non-null loop, so a replayed subscription had no consumer and
ReplayAsync never re-registered the post-reconnect item handles. ReplayAsync
now recreates the EventPump (RestartEventPumpForReplay) and rebinds the
SubscriptionRegistry per subscription with the fresh item handles returned by
the post-reconnect SubscribeBulkAsync, via new SubscriptionRegistry.SnapshotEntries
and Rebind APIs.

Regression tests: DataTypeMapTests (every code incl. Int64), SubscriptionRegistry
Tests (Rebind/SnapshotEntries), EventPumpStreamFaultTests (faulted pump dead,
fresh pump resumes dispatch).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/Browse/DataTypeMap.cs

@@ -8,6 +8,14 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browse;
 ///     to <see cref="DriverDataType.String"/> for unknown codes — keeps wire compatibility
 ///     with deployed configs while we tighten this through the parity matrix.
 /// </summary>
+/// <remarks>
+///     Code <c>6</c> (Int64) extends the contiguous 0..5 scheme so the map covers the same
+///     seven Galaxy data types <c>MxValueDecoder</c> / <c>MxValueEncoder</c> already decode
+///     and encode (Boolean, Int32, Int64, Float32, Float64, String, DateTime). Without it an
+///     Int64 attribute fell through to the <see cref="DriverDataType.String"/> default,
+///     creating a String address-space node while runtime reads decoded a boxed <c>long</c> —
+///     a metadata / coercion mismatch (Driver.Galaxy-002).
+/// </remarks>
 internal static class DataTypeMap
 {
     public static DriverDataType Map(int mxDataType) => mxDataType switch
@@ -18,6 +26,7 @@ internal static class DataTypeMap
         3 => DriverDataType.Float64,
         4 => DriverDataType.String,
         5 => DriverDataType.DateTime,
+        6 => DriverDataType.Int64,
         _ => DriverDataType.String,
     };
 }