feat(datapacks): add ironchest recipes and datapack sync automation

- Add crafting recipes for copper, iron, gold, and diamond chests using IronChest mod
- Remove vanilla copper chest recipe to prevent conflicts
- Introduce `.env.example` for local world configuration
- Add `bash/sync-datapacks-to-world.sh` script to mirror datapacks to Minecraft world saves
  - Supports one-time sync and watch mode for real-time updates
  - Uses `rsync` for efficient file synchronization

datapacks/m2621/data/minecraft/recipe/copper_chest.json

@@ -1,7 +1,5 @@
 {
   "type": "minecraft:crafting_shapeless",
-  "ingredients": [
-    "minecraft:copper_ingot"
-  ],
-  "result": {"id": "minecraft:copper_chest", "count": 0}
-}
+  "ingredients": [],
+  "result": {"item": "minecraft:air", "count": 0}
+}