feat(useragent): callouts feature for approving new things

useragent/lib/features/callouts/callout_manager.dart

@@ -0,0 +1,57 @@
+import 'package:arbiter/features/callouts/active_callout.dart';
+import 'package:arbiter/features/callouts/callout_event.dart';
+import 'package:arbiter/features/callouts/types/sdk_connect_approve.dart'
+    as connect_approve;
+import 'package:arbiter/proto/client.pb.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'callout_manager.g.dart';
+
+@Riverpod(keepAlive: true)
+class CalloutManager extends _$CalloutManager {
+  @override
+  Map<String, ActiveCallout> build() {
+    ref.listen(connect_approve.connectApproveEventsProvider, (_, next) {
+      next.whenData(_processEvent);
+    });
+    return {};
+  }
+
+  void _processEvent(CalloutEvent event) {
+    switch (event) {
+      case CalloutEventAdded(:final id, :final data):
+        state = {...state, id: _toActiveCallout(id, data)};
+      case CalloutEventCancelled(:final id):
+        state = {...state}..remove(id);
+    }
+  }
+
+  Future<void> sendDecision(String id, bool approved) async {
+    final callout = state[id];
+    if (callout == null) return;
+    switch (callout.data) {
+      case ConnectApprovalData(:final pubkey):
+        await connect_approve.sendDecision(ref, pubkey, approved);
+    }
+    dismiss(id);
+  }
+
+  void dismiss(String id) {
+    state = {...state}..remove(id);
+  }
+}
+
+ActiveCallout _toActiveCallout(String id, CalloutData data) => switch (data) {
+  ConnectApprovalData(:final clientInfo) => ActiveCallout(
+    id: id,
+    title: 'Connection Request',
+    description: _clientDisplayName(clientInfo) != null
+        ? '${_clientDisplayName(clientInfo)} is requesting a connection.'
+        : 'An SDK client is requesting a connection.',
+    addedAt: DateTime.now(),
+    data: data,
+  ),
+};
+
+String? _clientDisplayName(ClientInfo info) =>
+    info.hasName() && info.name.isNotEmpty ? info.name : null;