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>

docs/ClientPackaging.md

@@ -8,7 +8,7 @@ in [Toolchain Links](./ToolchainLinks.md) when a command is missing from
 ## Shared Inputs
 
 All clients generate bindings from the shared protobuf files under
-`src/MxGateway.Contracts/Protos`. Regenerate the published client descriptor
+`src/ZB.MOM.WW.MxGateway.Contracts/Protos`. Regenerate the published client descriptor
 after changing either `.proto` file or `clients/proto/proto-inputs.json`:
 
 ```powershell
@@ -35,37 +35,37 @@ machine boundary or uses a production certificate.
 ## .NET
 
 The .NET client uses .NET 10 and references
-`src/MxGateway.Contracts/MxGateway.Contracts.csproj` for generated C# contract
+`src/ZB.MOM.WW.MxGateway.Contracts/ZB.MOM.WW.MxGateway.Contracts.csproj` for generated C# contract
 types. `clients/dotnet/generated` remains reserved for client-local generator
 output if the client later decouples from the contracts project.
 
 Regenerate the generated C# contract types:
 
 ```powershell
-dotnet build src/MxGateway.Contracts/MxGateway.Contracts.csproj
+dotnet build src/ZB.MOM.WW.MxGateway.Contracts/ZB.MOM.WW.MxGateway.Contracts.csproj
 ```
 
 Build and test from the repository root:
 
 ```powershell
-dotnet build clients/dotnet/MxGateway.Client.sln
-dotnet test clients/dotnet/MxGateway.Client.sln --no-build
+dotnet build clients/dotnet/ZB.MOM.WW.MxGateway.Client.sln
+dotnet test clients/dotnet/ZB.MOM.WW.MxGateway.Client.sln --no-build
 ```
 
 Create local package artifacts:
 
 ```powershell
 $dotnetPackageOutput = Join-Path (Get-Location) 'artifacts/clients/dotnet'
-dotnet pack clients/dotnet/MxGateway.Client/MxGateway.Client.csproj -c Release -p:PackageOutputPath="$dotnetPackageOutput"
-dotnet publish clients/dotnet/MxGateway.Client.Cli/MxGateway.Client.Cli.csproj -c Release -o artifacts/clients/dotnet/mxgw-dotnet
+dotnet pack clients/dotnet/ZB.MOM.WW.MxGateway.Client/ZB.MOM.WW.MxGateway.Client.csproj -c Release -p:PackageOutputPath="$dotnetPackageOutput"
+dotnet publish clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli/ZB.MOM.WW.MxGateway.Client.Cli.csproj -c Release -o artifacts/clients/dotnet/mxgw-dotnet
 ```
 
 Run the CLI from source:
 
 ```powershell
-dotnet run --project clients/dotnet/MxGateway.Client.Cli -- version --json
-dotnet run --project clients/dotnet/MxGateway.Client.Cli -- smoke --endpoint "http://$env:MXGATEWAY_ENDPOINT" --api-key-env MXGATEWAY_API_KEY --item $env:MXGATEWAY_TEST_ITEM --json
-dotnet run --project clients/dotnet/MxGateway.Client.Cli -- smoke --endpoint "https://mxgateway.example.local:5001" --tls --ca-file C:\certs\mxgateway-ca.pem --server-name mxgateway.example.local --api-key-env MXGATEWAY_API_KEY --item $env:MXGATEWAY_TEST_ITEM --json
+dotnet run --project clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli -- version --json
+dotnet run --project clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli -- smoke --endpoint "http://$env:MXGATEWAY_ENDPOINT" --api-key-env MXGATEWAY_API_KEY --item $env:MXGATEWAY_TEST_ITEM --json
+dotnet run --project clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli -- smoke --endpoint "https://mxgateway.example.local:5001" --tls --ca-file C:\certs\mxgateway-ca.pem --server-name mxgateway.example.local --api-key-env MXGATEWAY_API_KEY --item $env:MXGATEWAY_TEST_ITEM --json
 ```
 
 ## Go