feat: record who created join codes and who added each node [CI]

backend/src/MoShiro.Backend.Application/Auth/AuthModels.cs

@@ -15,6 +15,9 @@ public sealed record Principal(PrincipalKind Kind, IReadOnlySet<string> Capabili
     /// <summary>会话是怎么登录的（<see cref="AuthMethods"/>）：只有 passkey 登录的会话以后能提权。API key 为空。</summary>
     public string AuthMethod { get; init; } = "";
 
+    /// <summary>审计和归属里显示的名字：用户名，或者 <c>key:令牌名</c>。</summary>
+    public string Label => Kind == PrincipalKind.Token && UserId is null ? "key:" + (Username ?? TokenId) : Username ?? "anonymous";
+
     public static Principal Anonymous { get; } = new(PrincipalKind.Anonymous, new HashSet<string>(), null, null, null, null);
 
     public bool Has(string capability) => capability == Capability.Authenticated ? Kind != PrincipalKind.Anonymous : Capabilities.Contains(capability);