feat(server): 管理页运维信息、首 Key 展示与 Key 最近使用

src/BiSheng.Server/Auth/ApiKeyAuthHandler.cs

@@ -64,6 +64,21 @@ protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
             return AuthenticateResult.Fail("Invalid or inactive API key.");
         }
 
+        // 节流更新 LastUsedAt，避免每次请求都写库
+        var now = DateTime.UtcNow;
+        if (key.LastUsedAt is null || now - key.LastUsedAt.Value > TimeSpan.FromMinutes(5))
+        {
+            key.LastUsedAt = now;
+            try
+            {
+                await db.SaveChangesAsync();
+            }
+            catch (Exception ex)
+            {
+                Logger.LogDebug(ex, "更新 ApiKey.LastUsedAt 失败（不影响认证）");
+            }
+        }
+
         var claims = new[]
         {
             new Claim(ClaimTypes.NameIdentifier, key.UserId.ToString()),

src/BiSheng.Server/Data/Entities/ApiKey.cs

@@ -23,6 +23,9 @@ public class ApiKey
 
     public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 
+    /// <summary>最近一次成功通过此 Key 认证的时间（UTC）；未使用过为 null</summary>
+    public DateTime? LastUsedAt { get; set; }
+
     // Navigation
     [ForeignKey(nameof(UserId))]
     public User User { get; set; } = null!;