feat: declareService — persist a host service via the new RPC

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/src/hub_client.dart

@@ -423,6 +423,25 @@ class HubClient {
     return r.services;
   }
 
+  /// Declare a host service in the operator config (`services:`).
+  /// Returns whether a daemon restart is required for it to take
+  /// effect (true today — services are read at start). Throws
+  /// ALREADY_EXISTS when the name is taken.
+  Future<bool> declareService({
+    required String name,
+    required String endpoint,
+    String healthPath = '',
+    List<String> tags = const [],
+  }) async {
+    final r = await _admin.declareService(pb.DeclareServiceRequest(
+      name: name,
+      endpoint: endpoint,
+      healthPath: healthPath,
+      tags: tags,
+    ));
+    return r.restartRequired;
+  }
+
   /// Compare local hub version vs. release-channel manifest.
   /// Network failures land in `manifestReachable=false` rather
   /// than as exceptions — Studio renders that case as a quiet