fix(addons): bring silverlabs packs into schema compliance

- recipes: add unlock { context: always_unlocked } to all spark_pet and lobby_transfer recipes (1.20+ requirement) — fixes mc-lobby crash loop
- spark_dragon entity_sensor: wrap in subsensors[] and convert sensor_range → range [a,b] per 1.21 schema
- anthrax_cat interact: wrap event/filters in on_interact to match Bedrock 1.21 interact schema
- block format_version: bump mailbox and smart_crafting_table to 1.21.60
- item icons: replace { texture: X } with shorthand string form
- heyhe_egg description: replace bare category with menu_category block

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

addon/anthrax_cat_BP/items/anthrax_cat.json

@@ -10,9 +10,7 @@
     },
     "components": {
       "minecraft:max_stack_size": 16,
-      "minecraft:icon": {
-        "texture": "anthrax_cat"
-      },
+      "minecraft:icon": "anthrax_cat",
       "minecraft:entity_placer": {
         "entity": "silverlabs:anthrax_cat"
       }