feat: proxy cmd support

Fixes #949

test/proxy_command_test.dart

@@ -0,0 +1,137 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:server_box/data/model/server/proxy_command_config.dart';
+import 'package:server_box/data/model/server/server_private_info.dart';
+
+void main() {
+  group('ProxyCommandConfig Tests', () {
+    test('should create ProxyCommandConfig with required fields', () {
+      const config = ProxyCommandConfig(
+        command: 'cloudflared access ssh --hostname %h',
+        timeout: Duration(seconds: 30),
+        requiresExecutable: true,
+        executableName: 'cloudflared',
+      );
+
+      expect(config.command, equals('cloudflared access ssh --hostname %h'));
+      expect(config.timeout.inSeconds, equals(30));
+      expect(config.requiresExecutable, isTrue);
+      expect(config.executableName, equals('cloudflared'));
+    });
+
+    test('should get final command with placeholders replaced', () {
+      const config = ProxyCommandConfig(
+        command: 'cloudflared access ssh --hostname %h --port %p',
+        timeout: Duration(seconds: 30),
+      );
+
+      final finalCommand = config.getFinalCommand(
+        hostname: 'example.com',
+        port: 22,
+        user: 'testuser',
+      );
+
+      expect(finalCommand, equals('cloudflared access ssh --hostname example.com --port 22'));
+    });
+
+    test('should handle all placeholders correctly', () {
+      const config = ProxyCommandConfig(
+        command: 'ssh -W %h:%p -l %r bastion.example.com',
+        timeout: Duration(seconds: 10),
+      );
+
+      final finalCommand = config.getFinalCommand(
+        hostname: 'target.example.com',
+        port: 2222,
+        user: 'admin',
+      );
+
+      expect(finalCommand, equals('ssh -W target.example.com:2222 -l admin bastion.example.com'));
+    });
+
+    test('should validate presets from map', () {
+      final presets = proxyCommandPresets;
+
+      final cloudflareConfig = presets['cloudflare_access'];
+      expect(cloudflareConfig, isNotNull);
+      expect(cloudflareConfig!.command, equals('cloudflared access ssh --hostname %h'));
+      expect(cloudflareConfig.requiresExecutable, isTrue);
+      expect(cloudflareConfig.executableName, equals('cloudflared'));
+
+      final sshBastionConfig = presets['ssh_via_bastion'];
+      expect(sshBastionConfig, isNotNull);
+      expect(sshBastionConfig!.command, equals('ssh -W %h:%p bastion.example.com'));
+      expect(sshBastionConfig.requiresExecutable, isFalse);
+
+      final ncConfig = presets['nc_netcat'];
+      expect(ncConfig, isNotNull);
+      expect(ncConfig!.command, equals('nc %h %p'));
+      expect(ncConfig.requiresExecutable, isFalse);
+
+      final socatConfig = presets['socat'];
+      expect(socatConfig, isNotNull);
+      expect(socatConfig!.command, equals('socat - PROXY:%h:%p,proxyport=8080'));
+      expect(socatConfig.requiresExecutable, isFalse);
+    });
+  });
+
+  group('Spi with ProxyCommand Tests', () {
+    test('should create Spi with ProxyCommand configuration', () {
+      final spi = Spi(
+        name: 'Test Server',
+        ip: 'example.com',
+        port: 22,
+        user: 'testuser',
+        pwd: 'testpass',
+        proxyCommand: const ProxyCommandConfig(
+          command: 'cloudflared access ssh --hostname %h',
+          timeout: Duration(seconds: 30),
+          requiresExecutable: true,
+          executableName: 'cloudflared',
+        ),
+      );
+
+      expect(spi.name, equals('Test Server'));
+      expect(spi.proxyCommand, isNotNull);
+      expect(spi.proxyCommand!.command, equals('cloudflared access ssh --hostname %h'));
+      expect(spi.proxyCommand!.requiresExecutable, isTrue);
+    });
+
+    test('should handle Spi without ProxyCommand', () {
+      final spi = Spi(
+        name: 'Test Server',
+        ip: 'example.com',
+        port: 22,
+        user: 'testuser',
+        pwd: 'testpass',
+      );
+
+      expect(spi.proxyCommand, isNull);
+    });
+
+    test('should serialize and deserialize Spi with ProxyCommand', () {
+      final originalSpi = Spi(
+        name: 'Test Server',
+        ip: 'example.com',
+        port: 22,
+        user: 'testuser',
+        pwd: 'testpass',
+        proxyCommand: const ProxyCommandConfig(
+          command: 'cloudflared access ssh --hostname %h',
+          timeout: Duration(seconds: 30),
+          requiresExecutable: true,
+          executableName: 'cloudflared',
+        ),
+      );
+
+      final json = originalSpi.toJson();
+      final deserializedSpi = Spi.fromJson(json);
+
+      expect(deserializedSpi.name, equals(originalSpi.name));
+      expect(deserializedSpi.ip, equals(originalSpi.ip));
+      expect(deserializedSpi.proxyCommand, isNotNull);
+      expect(deserializedSpi.proxyCommand!.command, equals(originalSpi.proxyCommand!.command));
+      expect(deserializedSpi.proxyCommand!.requiresExecutable, equals(originalSpi.proxyCommand!.requiresExecutable));
+      expect(deserializedSpi.proxyCommand!.executableName, equals(originalSpi.proxyCommand!.executableName));
+    });
+  });
+}