pack: economy MVP -- Numismatics + Patchouli + welcome flow, bump to 0.18.0

Adds the currency layer and the first-join experience.

Mods:
- Create: Numismatics 1.0.20  (currency, vendor blocks, piggy banks)
- Patchouli 1.21.1-93         (kept in pack for future rich manual book)

KubeJS scripts (server_scripts/):
- economy_policy.js  remove ALL Waystones recipes; remove coin recipes
                     only (piggy banks etc. stay craftable for now)
- welcome.js         first-login grant: 1 waystone + vanilla written-book
                     "Brass & Sigil Manual v1" (5 pages: welcome,
                     waystones, money, spawn plots, rules). Per-player
                     flag bnsWelcomeGranted in persistentData gates it.

KubeJS scripts (client_scripts/):
- jei_hides.js       hide all Waystones items + 4 coin denominations from
                     the JEI ingredient list. Combined with the recipe
                     removal players never encounter these items via
                     normal play -- only via the welcome grant or the
                     bank exchange.

The written-book manual is the MVP placeholder. When more content lands
(plot system, dynamic exchange, etc.) it'll be replaced by a proper
Patchouli book authored as a tweak jar -- Patchouli's already in the
lockfile so no mod-add will be needed at that point.

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": "0.17.0",
+  "version": "0.18.0",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",
@@ -481,6 +481,28 @@
       "sha1": "488bc70db3730f209e65cbda04c36dbc3918c448",
       "size": 878265,
       "side": "both"
+    },
+    {
+      "source": "modrinth",
+      "slug": "numismatics",
+      "versionId": "guON3qvQ",
+      "version": "1.0.20+neoforge-mc1.21.1",
+      "path": "mods/CreateNumismatics-1.0.20+neoforge-mc1.21.1.jar",
+      "url": "https://cdn.modrinth.com/data/Jdbbtt0i/versions/guON3qvQ/CreateNumismatics-1.0.20%2Bneoforge-mc1.21.1.jar",
+      "sha1": "9883bfd6fef5bd5068f9174ddccba5047849c922",
+      "size": 693446,
+      "side": "both"
+    },
+    {
+      "source": "modrinth",
+      "slug": "patchouli",
+      "versionId": "BIogJv2D",
+      "version": "1.21.1-93-neoforge",
+      "path": "mods/Patchouli-1.21.1-93-NEOFORGE.jar",
+      "url": "https://cdn.modrinth.com/data/nU0bVIaL/versions/BIogJv2D/Patchouli-1.21.1-93-NEOFORGE.jar",
+      "sha1": "5413bb9b8fc35ebe46b06b48bf9afafbd8471140",
+      "size": 646777,
+      "side": "both"
     }
   ],
   "defaultServer": {