feat(pet): add Hey Hey chicken pet addon

Tameable white chicken modelled on Hey Hey from Moana — custom plump
geometry, waddly walk/peck animations, hatching egg item, and vanilla
chicken sounds. Mounted on all 4 servers via docker-compose.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

addon/heyhe_pet_BP/items/heyhe_egg.json

@@ -0,0 +1,31 @@
+{
+  "format_version": "1.21.0",
+  "minecraft:item": {
+    "description": {
+      "identifier": "silverlabs:heyhe_egg",
+      "category": "Nature"
+    },
+    "components": {
+      "minecraft:max_stack_size": 16,
+      "minecraft:icon": {
+        "texture": "heyhe_egg"
+      },
+      "minecraft:entity_placer": {
+        "entity": "silverlabs:heyhe_egg",
+        "dispense_on": [
+          "grass",
+          "dirt",
+          "stone",
+          "sand",
+          "gravel",
+          "coarse_dirt",
+          "podzol",
+          "mycelium",
+          "farmland",
+          "grass_path",
+          "dirt_with_roots"
+        ]
+      }
+    }
+  }
+}