Four tiers per brand: RZX 60/70/80/90 and RZ 70/80/800/900

Model name is display only; performance and price follow brand and tier.
Tier physical traits: power pins 6/8/8/8+8 and fans 1/2/3/3.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/Decentralized/Items.cs

@@ -63,7 +63,7 @@ namespace Decentralized
 
         // ---------- 显卡 ----------
 
-        /// <summary>RZX70 → "RZX 70"，RZX80Ti → "RZX 80 Ti"，RZ6800 → "RZ 6800"。</summary>
+        /// <summary>RZX70 → "RZX 70"，RZ800 → "RZ 800"。</summary>
         public static string DisplayModel(string model) => Regex.Replace(Regex.Replace(model, @"(?<=[A-Za-z])(?=\d)", " "), @"(?<=\d)(?=[A-Z])", " ");
 
         private static GameItem CreateGpu(HardwareSpec spec)