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.Worker/Bootstrap/WorkerLogRedactor.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+
+namespace ZB.MOM.WW.MxGateway.Worker.Bootstrap;
+
+/// <summary>
+/// Redacts sensitive fields from worker log messages.
+/// </summary>
+public static class WorkerLogRedactor
+{
+    /// <summary>
+    /// Replacement text for redacted values.
+    /// </summary>
+    public const string RedactedValue = "[redacted]";
+
+    private static readonly string[] SensitiveFieldNameParts =
+    [
+        "nonce",
+        "secret",
+        "password",
+        "token",
+        "credential",
+        "apikey",
+        "api_key",
+    ];
+
+    /// <summary>
+    /// Redacts sensitive field values from a log field dictionary.
+    /// </summary>
+    /// <param name="fields">Dictionary of field names and values.</param>
+    public static Dictionary<string, object?> RedactFields(IReadOnlyDictionary<string, object?> fields)
+    {
+        Dictionary<string, object?> redactedFields = [];
+
+        foreach (KeyValuePair<string, object?> field in fields)
+        {
+            redactedFields[field.Key] = RedactValue(field.Key, field.Value);
+        }
+
+        return redactedFields;
+    }
+
+    /// <summary>
+    /// Redacts a single value if its field name contains sensitive keywords.
+    /// </summary>
+    /// <param name="fieldName">Name of the field to check.</param>
+    /// <param name="value">Value to redact if sensitive.</param>
+    public static object? RedactValue(string fieldName, object? value)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+
+        foreach (string sensitiveFieldNamePart in SensitiveFieldNameParts)
+        {
+            if (fieldName.IndexOf(sensitiveFieldNamePart, StringComparison.OrdinalIgnoreCase) >= 0)
+            {
+                return RedactedValue;
+            }
+        }
+
+        return value;
+    }
+}