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/spark_pet_BP/recipes/dragon_nest_jungle.json

@@ -2,6 +2,7 @@
   "format_version": "1.21.0",
   "minecraft:recipe_shaped": {
     "description": { "identifier": "silverlabs:dragon_nest_jungle_recipe" },
+    "unlock": { "context": "always_unlocked" },
     "tags": ["crafting_table"],
     "pattern": [
       "S S",