feat: simple NWC flow

closes #19

lib/pages/settings_wallet.dart

@@ -0,0 +1,77 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:zap_stream_flutter/const.dart';
+import 'package:zap_stream_flutter/i18n/strings.g.dart';
+import 'package:zap_stream_flutter/login.dart';
+import 'package:zap_stream_flutter/theme.dart';
+import 'package:zap_stream_flutter/widgets/button.dart';
+
+class SettingsWalletPage extends StatefulWidget {
+  const SettingsWalletPage({super.key});
+
+  @override
+  State<StatefulWidget> createState() => _Inner();
+}
+
+class _Inner extends State<SettingsWalletPage> {
+  late final TextEditingController _uri;
+  String? _error;
+
+  @override
+  void initState() {
+    _uri = TextEditingController();
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final pubkey = ndk.accounts.getPublicKey();
+    if (pubkey == null) return Text(t.wallet.error.logged_out);
+
+    return ValueListenableBuilder(
+      valueListenable: loginData,
+      builder: (context, state, child) {
+        if (state?.wallet == null) {
+          return Column(
+            spacing: 8,
+            children: [
+              TextField(
+                controller: _uri,
+                decoration: InputDecoration(labelText: t.wallet.connect_wallet),
+              ),
+              BasicButton.text(
+                t.button.connect,
+                onTap: (context) async {
+                  try {
+                    await ndk.nwc.connect(_uri.text);
+                    final cfg = WalletConfig(
+                      type: WalletType.nwc,
+                      data: _uri.text,
+                    );
+                    loginData.value = LoginAccount(
+                      type: loginData.value!.type,
+                      pubkey: loginData.value!.pubkey,
+                      privateKey: loginData.value!.privateKey,
+                      signerRelays: loginData.value!.signerRelays,
+                      wallet: cfg,
+                    );
+                    if (context.mounted) {
+                      context.pop();
+                    }
+                  } catch (e) {
+                    setState(() {
+                      _error = e is String ? e : e.toString();
+                    });
+                  }
+                },
+              ),
+              if (_error != null)
+                Text(_error!, style: TextStyle(color: WARNING)),
+            ],
+          );
+        }
+        return SizedBox.shrink();
+      },
+    );
+  }
+}