feat(smart-crafting): add smart crafting table using private chest inventory

Adds an upgraded crafting block that scans the player's owned private chests
and aggregates their contents with the personal inventory when deciding which
recipes are craftable. Ingredients are consumed from the player first then
from chests; the result goes to the player (or drops at their feet).

Also redraws the post_office and mailbox block textures via a new
scripts/build-textures.py generator.

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

smart-crafting-addon/smart_crafting_BP/recipes/smart_crafting_table.json

@@ -0,0 +1,19 @@
+{
+  "format_version": "1.21.0",
+  "minecraft:recipe_shapeless": {
+    "description": {
+      "identifier": "silverlabs:smart_crafting_table_recipe"
+    },
+    "tags": ["crafting_table"],
+    "unlock": { "context": "AlwaysUnlocked" },
+    "ingredients": [
+      { "item": "minecraft:crafting_table" },
+      { "item": "minecraft:gold_ingot" },
+      { "item": "minecraft:redstone" }
+    ],
+    "result": {
+      "item": "silverlabs:smart_crafting_table",
+      "count": 1
+    }
+  }
+}