Verify state on login

This fixes "already logged in errors" if you started logging in before cancelling, and then trying again.

lib/controllers/auth_url.dart

@@ -23,10 +23,8 @@ class AuthUrlController extends AsyncNotifier<OAuthAuthCodeResponse> {
         ),
       );
 
-  static final provider =
-      AsyncNotifierProvider.family<
-        AuthUrlController,
-        OAuthAuthCodeResponse,
-        Uri
-      >(AuthUrlController.new);
+  static final provider = AsyncNotifierProvider.family
+      .autoDispose<AuthUrlController, OAuthAuthCodeResponse, Uri>(
+        AuthUrlController.new,
+      );
 }

lib/pages/select_server.dart

@@ -58,6 +58,9 @@ class SelectServerPage extends HookConsumerWidget {
             await ref.watch(LaunchHelper.provider).launchUrl(codeResponse.url);
 
             AppLinks().uriLinkStream.listen((encodedUri) async {
+              final state = encodedUri.queryParameters["state"];
+              if (state != codeResponse.state) return;
+
               final code = encodedUri.queryParameters["code"];
 
               if (code != null) {

lib/pages/verify.dart

@@ -2,6 +2,7 @@ import "package:flutter/material.dart";
 import "package:flutter_hooks/flutter_hooks.dart";
 import "package:hooks_riverpod/hooks_riverpod.dart";
 import "package:nexus/controllers/client.dart";
+import "package:nexus/pages/settings.dart";
 import "package:nexus/widgets/appbar.dart";
 import "package:nexus/helpers/required_validator_helper.dart";
 
@@ -32,7 +33,15 @@ class VerifyPage extends HookConsumerWidget {
     }
 
     return Scaffold(
-      appBar: Appbar(),
+      appBar: Appbar(
+        actions: .new([
+          IconButton(
+            onPressed: () =>
+                showDialog(context: context, builder: (_) => SettingsPage()),
+            icon: Icon(Icons.settings),
+          ),
+        ]),
+      ),
       body: AlertDialog(
         title: Text("Verify"),
         content: Form(