feat(client): getDefaultScope / setDefaultScope wrappers

Studio's upcoming default_scope editor in Settings calls
through these wrappers. Both return a record with the live
`scope` and the catalog-known publisher shortlist so the UI
can render a typeahead while letting operators paste private
publisher segments freely.

Bindings regenerated from fai_platform/proto.

dart analyze + dart test green (4 tests).

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

lib/src/hub_client.dart

@@ -158,6 +158,35 @@ class HubClient {
     return r.events;
   }
 
+  /// Read the operator's `default_scope:` — the ordered list of
+  /// provider segments the bare-form capability resolver
+  /// consults when a flow names a capability without an explicit
+  /// `<provider>/` prefix. Also returns a sorted list of catalog-
+  /// known publisher segments so editors can offer a typeahead
+  /// shortlist (arbitrary entries are still allowed).
+  Future<({List<String> scope, List<String> knownProviders})>
+      getDefaultScope() async {
+    final r = await _admin.getDefaultScope(Empty());
+    return (
+      scope: List<String>.from(r.scope),
+      knownProviders: List<String>.from(r.knownProviders),
+    );
+  }
+
+  /// Replace the operator's `default_scope:`. The hub validates
+  /// the list (non-empty after trimming), persists to
+  /// `~/.fai/config.yaml`, and hot-swaps the in-memory copy
+  /// without a daemon restart. Returns the snapshot.
+  Future<({List<String> scope, List<String> knownProviders})>
+      setDefaultScope(List<String> scope) async {
+    final req = pb.SetDefaultScopeRequest()..scope.addAll(scope);
+    final r = await _admin.setDefaultScope(req);
+    return (
+      scope: List<String>.from(r.scope),
+      knownProviders: List<String>.from(r.knownProviders),
+    );
+  }
+
   /// Server-streaming audit-log subscription. The hub first
   /// replays up to [backfill] historical events (oldest-last so
   /// the receiver sees them in chronological order), then keeps