feat(useragent): initial connection impl

useragent/lib/screens/server_connection.dart

@@ -0,0 +1,60 @@
+import 'package:arbiter/providers/connection/connection_manager.dart';
+import 'package:arbiter/router.gr.dart';
+import 'package:auto_route/auto_route.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:sizer/sizer.dart';
+
+@RoutePage()
+class ServerConnectionScreen extends HookConsumerWidget {
+  const ServerConnectionScreen({super.key, this.arbiterUrl});
+
+  final String? arbiterUrl;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final connectionState = ref.watch(connectionManagerProvider);
+
+    if (connectionState.value != null) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        context.router.replace(const DashboardRouter());
+      });
+    }
+
+    final body = switch (connectionState) {
+      AsyncLoading() => const CircularProgressIndicator(),
+      AsyncError(:final error) => Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Text(
+            'Connection failed',
+            style: Theme.of(context).textTheme.headlineSmall,
+            textAlign: TextAlign.center,
+          ),
+          SizedBox(height: 1.5.h),
+          Text('$error', textAlign: TextAlign.center),
+          SizedBox(height: 2.h),
+
+          TextButton(
+            onPressed: () {
+              context.router.replace(const ServerInfoSetupRoute());
+            },
+            child: const Text('Back to server setup'),
+          ),
+        ],
+      ),
+      _ => const CircularProgressIndicator(),
+    };
+
+    return Scaffold(
+      appBar: AppBar(title: const Text('Connecting')),
+      body: Center(
+        child: Padding(
+          padding: EdgeInsets.symmetric(horizontal: 8.w),
+          child: body,
+        ),
+      ),
+    );
+  }
+}