fix(hysteria2): emit https server_url for sing-box realm outbound (#9642)

sing-box requires realm.server_url as a full URL (https://host:port).
Bare host:port caused "missing host in realm server_url" on import.
Also forward stun_servers and clear ResolveRealm success message.

Fixes #9635

v2rayN/ServiceLib/Models/CoreConfigs/SingboxConfig.cs

@@ -257,6 +257,7 @@ public class HyRealm4Sbox
     public string? server_url { get; set; }
     public string? token { get; set; }
     public string? realm_id { get; set; }
+    public List<string>? stun_servers { get; set; }
 }
 
 public class Server4Sbox : BaseServer4Sbox