pack: add Almost Unified 1.4.2 + bump to 0.12.0

Preemptive insurance against duplicate-item proliferation when more
metals-producing mods are added (e.g. when Power Grid lands, or any
future Mekanism/Thermal/etc. addition). Today's pack only has TFMG as
the metals provider so AU is largely a no-op now, but ships with sane
default tag preferences that activate automatically as duplicates appear.

Tiny mod (~290 KB jar), client-optional/server-required per Modrinth.

pack/pack.lock.json

@@ -1,7 +1,7 @@
 {
   "$schema": "Brass-and-Sigil pack.lock.json - generated, do not edit by hand unless you know what you are doing",
   "name": "Brass and Sigil",
-  "version": "0.11.0",
+  "version": "0.12.0",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",
@@ -382,6 +382,17 @@
       "sha1": "55fc0d529318620bd2ce7a635657014c5c98e189",
       "size": 4902096,
       "side": "both"
+    },
+    {
+      "source": "modrinth",
+      "slug": "almostunified",
+      "versionId": "e8iYxxI3",
+      "version": "1.21.1-1.4.2+neoforge",
+      "path": "mods/almostunified-neoforge-1.21.1-1.4.2.jar",
+      "url": "https://cdn.modrinth.com/data/sdaSaQEz/versions/e8iYxxI3/almostunified-neoforge-1.21.1-1.4.2.jar",
+      "sha1": "f9a58fa95780f4b045d30559c1fdaedaa7f0fba3",
+      "size": 295093,
+      "side": "both"
     }
   ],
   "defaultServer": {