Add Opencode (opencode.ai) integration via SSH tunnel

Features:
- Opencode AI chat interface
- SSH tunnel for secure API communication
- Auto-install Opencode on remote servers
- API key management with server-side storage
- Session history and management
- Integration with flutter_server_box server list

lib/data/model/app/menu/server_func.dart

@@ -13,7 +13,8 @@ enum ServerFuncBtn {
   iperf(),
   // pve(),
   systemd(1058),
-  portForward(1340);
+  portForward(1340),
+  opencode(1352);  // 添加 Opencode 按钮
 
   final int? addedVersion;
 
@@ -36,6 +37,13 @@ enum ServerFuncBtn {
       }
     }
 
+    // 自动添加 Opencode 按钮
+    if (opencode.addedVersion != null && cur >= opencode.addedVersion!) {
+      if (!list.contains(opencode.index)) {
+        list.add(opencode.index);
+      }
+    }
+
     if (list.length > originalLength) {
       prop.put(list);
     }
@@ -62,6 +70,7 @@ enum ServerFuncBtn {
     iperf => Icons.speed,
     systemd => MingCute.plugin_2_fill,
     portForward => Icons.compare_arrows,
+    opencode => Icons.smart_toy,  // Opencode 图标
   };
 
   String get toStr => switch (this) {
@@ -74,5 +83,6 @@ enum ServerFuncBtn {
     iperf => 'iperf',
     systemd => 'Systemd',
     portForward => libL10n.portForward,
+    opencode => 'Opencode',  // Opencode 按钮文字
   };
 }