feat: add MC 1.21.7/1.21.8 (protocol 772) support

1.21.7 and 1.21.8 share protocol 772. The only registry change from
1.21.6 is one new item (music_disc_lava_chicken). All other palettes
(blocks, entities, packets, entity metadata, structured components)
are unchanged and reuse 1.21.6 versions.

Changes:
- Add MC_1_21_7_Version (772) constant
- Add "1.21.7" / "1.21.8" version mappings in ProtocolHandler
- Add MusicDiscLavaChicken to ItemType enum
- Generate ItemPalette1217 (1416 items) for the new item palette
- Update all version upper-bound checks from MC_1_21_6 to MC_1_21_7
- Update MCHighestVersion to "1.21.8"

Made-with: Cursor

MinecraftClient/Protocol/ProtocolHandler.cs

@@ -154,7 +154,7 @@ namespace MinecraftClient.Protocol
             {
                 4, 5, 47, 107, 108, 109, 110, 210, 315, 316, 335, 338, 340, 393, 401, 404, 477, 480, 485, 490, 498, 573,
                 575, 578, 735, 736, 751, 753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764, 765, 766, 767, 768,
-                769, 770, 771
+                769, 770, 771, 772
             };
 
             if (Array.IndexOf(suppoertedVersionsProtocol18, protocolVersion) > -1)
@@ -362,6 +362,9 @@ namespace MinecraftClient.Protocol
                         return 770;
                     case "1.21.6":
                         return 771;
+                    case "1.21.7":
+                    case "1.21.8":
+                        return 772;
                     default:
                         return 0;
                 }
@@ -447,6 +450,7 @@ namespace MinecraftClient.Protocol
                 769 => "1.21.4",
                 770 => "1.21.5",
                 771 => "1.21.6",
+                772 => "1.21.7",
                 _ => "0.0"
             };
         }