rename: prefix gateway projects/namespaces with ZB.MOM.WW + sln→slnx

Apply the ZB.MOM.WW. prefix to all gateway-side projects, folders,
.csproj/.sln contents, C# namespaces, using directives, generated proto
C# (csharp_namespace + checked-in generated files), InternalsVisibleTo
attributes, project-name string literals (LoadProject, .sln lookups,
worker exe paths, staticwebassets manifest), and the install/script/doc
references that point at any of the above. Migrate the solution from
.sln to .slnx via `dotnet sln migrate` and delete the old file.

External-runtime identifiers are intentionally NOT prefixed so external
configuration keeps working:
- GatewayMetrics.cs MeterName ("MxGateway.Server")
- DashboardAuthenticationDefaults Scheme/Policy ("MxGateway.Dashboard")
- GatewayRequestLoggingMiddleware logger category ("MxGateway.Request")
- StaRuntime thread name ("MxGateway.Worker.STA")
- appsettings.json root section "MxGateway" + env-var prefix
  MxGateway__... and secret-name MxGateway:ApiKeyPepper
- C:\ProgramData\MxGateway\ data dir paths

Also fixes two tests that were not rename-related but became visible
while validating the rename:

- WorkerLiveMxAccessSmokeTests.ShutDownAsync: cancellation that the
  gateway service correctly maps to RpcException(Cancelled) per gRPC
  convention was being misclassified as a stream fault. Added a sibling
  catch on RpcException with StatusCode.Cancelled.

- IntegrationTestEnvironment.ResolveRepositoryRoot: extracted IsRepositoryRoot
  and made it accept either a .git marker OR a .sln/.slnx next to src/
  so the worker-exe walker works in non-git working copies.

clients/proto/proto-inputs.json's protoRoot updated to point at
src/ZB.MOM.WW.MxGateway.Contracts/Protos.

Verified by `dotnet build` and a full `dotnet test` of the .slnx with
MXGATEWAY_RUN_LIVE_{MXACCESS,LDAP,GALAXY}_TESTS=1:
  Tests: 472/472 pass
  Worker.Tests: 280/280 pass (4 dev-rig [Fact(Skip=...)] skipped)
  IntegrationTests: 18/18 pass

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

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Dashboard/DashboardApiKeyAuthorizationTests.cs

@@ -0,0 +1,65 @@
+using System.Security.Claims;
+using Microsoft.Extensions.Options;
+using ZB.MOM.WW.MxGateway.Server.Configuration;
+using ZB.MOM.WW.MxGateway.Server.Dashboard;
+
+namespace ZB.MOM.WW.MxGateway.Tests.Gateway.Dashboard;
+
+public sealed class DashboardApiKeyAuthorizationTests
+{
+    [Fact]
+    public void CanManage_AuthenticatedUserWithShortRequiredGroupClaim_ReturnsTrue()
+    {
+        DashboardApiKeyAuthorization authorization = CreateAuthorization();
+        ClaimsPrincipal user = CreatePrincipal("GwAdmin");
+
+        Assert.True(authorization.CanManage(user));
+    }
+
+    [Fact]
+    public void CanManage_AuthenticatedUserWithRequiredGroupDnClaim_ReturnsTrue()
+    {
+        DashboardApiKeyAuthorization authorization = CreateAuthorization();
+        ClaimsPrincipal user = CreatePrincipal("ou=GwAdmin,ou=groups,dc=lmxopcua,dc=local");
+
+        Assert.True(authorization.CanManage(user));
+    }
+
+    [Fact]
+    public void CanManage_AnonymousUser_ReturnsFalse()
+    {
+        DashboardApiKeyAuthorization authorization = CreateAuthorization();
+        ClaimsPrincipal user = new(new ClaimsIdentity());
+
+        Assert.False(authorization.CanManage(user));
+    }
+
+    [Fact]
+    public void CanManage_AuthenticatedUserWithoutRequiredGroup_ReturnsFalse()
+    {
+        DashboardApiKeyAuthorization authorization = CreateAuthorization();
+        ClaimsPrincipal user = CreatePrincipal("ReadOnly");
+
+        Assert.False(authorization.CanManage(user));
+    }
+
+    private static DashboardApiKeyAuthorization CreateAuthorization()
+    {
+        return new DashboardApiKeyAuthorization(Options.Create(new GatewayOptions
+        {
+            Ldap = new LdapOptions
+            {
+                RequiredGroup = "GwAdmin",
+            },
+        }));
+    }
+
+    private static ClaimsPrincipal CreatePrincipal(string group)
+    {
+        ClaimsIdentity identity = new(
+            [new Claim(DashboardAuthenticationDefaults.LdapGroupClaimType, group)],
+            DashboardAuthenticationDefaults.AuthenticationScheme);
+
+        return new ClaimsPrincipal(identity);
+    }
+}