Centralize admin auth with endpoint filter

Endpoints/EndpointHelpers.cs

@@ -11,10 +11,10 @@ internal static class EndpointHelpers
 {
     public static async Task<Player?> GetAuthenticatedPlayer(HttpContext ctx, AppDbContext db)
     {
-        if (ctx?.User?.Identity?.IsAuthenticated != true)
-        {
-            return null;
-        }
+        if (ctx?.User?.Identity?.IsAuthenticated != true) return null;
+
+        if (ctx.Items.TryGetValue(nameof(Player), out var cached) && cached is Player cachedPlayer)
+            return cachedPlayer;
 
         var idValue = ctx.User.FindFirstValue(ClaimTypes.NameIdentifier);
         if (string.IsNullOrWhiteSpace(idValue) || !Guid.TryParse(idValue, out var playerId))
@@ -28,7 +28,10 @@ internal static class EndpointHelpers
         if (existing is null)
         {
             await Infrastructure.PlayerIdentityExtensions.SignOutPlayerAsync(ctx);
+            return null;
         }
+
+        ctx.Items[nameof(Player)] = existing;
         return existing;
     }