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_RP/entity/heyhe_egg.entity.json

@@ -0,0 +1,20 @@
+{
+  "format_version": "1.10.0",
+  "minecraft:client_entity": {
+    "description": {
+      "identifier": "silverlabs:heyhe_egg",
+      "materials": {
+        "default": "entity_alphatest"
+      },
+      "textures": {
+        "default": "textures/entity/heyhe_egg"
+      },
+      "geometry": {
+        "default": "geometry.heyhe_egg"
+      },
+      "render_controllers": [
+        "controller.render.heyhe_egg"
+      ]
+    }
+  }
+}