review(Driver.Galaxy.Browser): fix mis-shifted MapSecurityClass codes (High)

Review at HEAD 7286d320. Driver.Galaxy.Browser-001 (High): MapSecurityClass codes 2-6 were
all shifted vs the runtime SecurityClassification enum (wrong security labels in the picker)
-> corrected all 7 arms + tests. -002: DisposeAsync swallows concurrent ObjectDisposedException.
-003 (ResolveApiKey dup) deferred to Contracts.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser/GalaxyBrowseSession.cs

@@ -146,28 +146,42 @@ internal sealed class GalaxyBrowseSession : IBrowseSession
 
     /// <summary>
     ///     Maps the Galaxy raw security-classification integer to a display string.
-    ///     Buckets: 0=FreeAccess, 1=Operate, 2=Tune, 3=Configure, 4=ViewOnly;
-    ///     anything else surfaces as <c>Unknown(N)</c>.
+    ///     Matches the <c>SecurityClassification</c> enum ordinals and the runtime
+    ///     <c>SecurityMap</c> in Driver.Galaxy:
+    ///     0=FreeAccess, 1=Operate, 2=SecuredWrite, 3=VerifiedWrite,
+    ///     4=Tune, 5=Configure, 6=ViewOnly; anything else surfaces as <c>Unknown(N)</c>.
     /// </summary>
-    private static string MapSecurityClass(int raw) => raw switch
+    // internal for unit-test access (InternalsVisibleTo on the src project).
+    internal static string MapSecurityClass(int raw) => raw switch
     {
         0 => "FreeAccess",
         1 => "Operate",
-        2 => "Tune",
-        3 => "Configure",
-        4 => "ViewOnly",
+        2 => "SecuredWrite",
+        3 => "VerifiedWrite",
+        4 => "Tune",
+        5 => "Configure",
+        6 => "ViewOnly",
         _ => $"Unknown({raw})",
     };
 
     /// <summary>
     ///     Idempotently tears down the underlying repository client. Swallows exceptions
     ///     on shutdown — the registry's reaper may be racing a client-initiated close.
+    ///     Both <see cref="SemaphoreSlim.Dispose"/> and the client dispose are wrapped
+    ///     in try/catch so a concurrent second dispose call never propagates.
     /// </summary>
     public async ValueTask DisposeAsync()
     {
         if (_disposed) return;
         _disposed = true;
-        _rootGate.Dispose();
+        try
+        {
+            _rootGate.Dispose();
+        }
+        catch (ObjectDisposedException)
+        {
+            // Concurrent DisposeAsync caller already disposed the gate — safe to ignore.
+        }
         try
         {
             await _client.DisposeAsync().ConfigureAwait(false);