Add Galaxy repository API and clients

docs/client-proto-generation.md

@@ -23,11 +23,15 @@ The source files listed by the manifest are:
 
 - `src/MxGateway.Contracts/Protos/mxaccess_gateway.proto`
 - `src/MxGateway.Contracts/Protos/mxaccess_worker.proto`
+- `src/MxGateway.Contracts/Protos/galaxy_repository.proto`
 
 `mxaccess_gateway.proto` defines the public gRPC service and shared DTOs.
 `mxaccess_worker.proto` is included in the descriptor because worker-aware
 tests and fake-worker clients need the same command, reply, event, value, and
-status shapes.
+status shapes. `galaxy_repository.proto` defines the read-only Galaxy
+Repository browse service used by clients to enumerate the deployed object
+hierarchy and dynamic attributes; see
+[Galaxy Repository Browse](./GalaxyRepository.md).
 
 ## Protocol Version