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/entities/heyhe_egg.json

@@ -0,0 +1,66 @@
+{
+  "format_version": "1.21.0",
+  "minecraft:entity": {
+    "description": {
+      "identifier": "silverlabs:heyhe_egg",
+      "is_spawnable": false,
+      "is_summonable": true,
+      "is_experimental": false
+    },
+
+    "components": {
+      "minecraft:type_family": {
+        "family": ["heyhe_egg"]
+      },
+      "minecraft:collision_box": {
+        "width": 0.5,
+        "height": 0.6
+      },
+      "minecraft:physics": {
+        "has_gravity": true,
+        "has_collision": true
+      },
+      "minecraft:pushable": {
+        "is_pushable": false,
+        "is_pushable_by_piston": false
+      },
+      "minecraft:health": {
+        "value": 5,
+        "max": 5
+      },
+      "minecraft:timer": {
+        "looping": false,
+        "time": 10,
+        "time_down_event": {
+          "event": "silverlabs:hatch",
+          "target": "self"
+        }
+      },
+      "minecraft:ambient_sound_interval": {
+        "event_name": "mob.chicken.egg",
+        "range": 0,
+        "value": 8
+      }
+    },
+
+    "events": {
+      "silverlabs:hatch": {
+        "sequence": [
+          {
+            "spawn_entity": {
+              "entities_to_spawn": [
+                {
+                  "entity_type": "silverlabs:heyhe_chicken",
+                  "num_to_spawn": 1
+                }
+              ]
+            }
+          },
+          {
+            "die": {}
+          }
+        ]
+      }
+    }
+  }
+}