Make the module installable: vendor core, point at release assets

What was on git could not be installed. foundry-module/ referenced core/ rather
than containing it, so an installed copy had no generator at all — it only ever
worked here because the live module directory had core/ copied in by hand.

core/ is now vendored into foundry-module/module/core/, minus cli.mjs and
test.mjs which are desk tools. module.json points manifest and download at
release assets, the way mapwright distributes, so a remote server can install by
URL without reaching into the repo tree.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

foundry-module/module.json

@@ -3,9 +3,34 @@
   "title": "DELVE — a dungeon layer for VANITY",
   "description": "Generates a coherent delve and sequences VANITY's Forge to stage it, one area at a time.",
   "version": "0.1.0",
-  "compatibility": { "minimum": "13", "verified": "14.365" },
-  "relationships": { "systems": [{ "id": "vanity", "type": "requires", "compatibility": { "minimum": "0.10.0" } }] },
-  "esmodules": ["module/vanity-delve.mjs"],
-  "styles": ["styles/vanity-delve.css"],
-  "authors": [{ "name": "slaguru666" }]
-}
+  "compatibility": {
+    "minimum": "13",
+    "verified": "14.365"
+  },
+  "relationships": {
+    "systems": [
+      {
+        "id": "vanity",
+        "type": "requires",
+        "compatibility": {
+          "minimum": "0.10.0"
+        }
+      }
+    ]
+  },
+  "esmodules": [
+    "module/vanity-delve.mjs"
+  ],
+  "styles": [
+    "styles/vanity-delve.css"
+  ],
+  "authors": [
+    {
+      "name": "slaguru666"
+    }
+  ],
+  "manifest": "https://github.com/slaguru666/vanity-delve/releases/latest/download/module.json",
+  "download": "https://github.com/slaguru666/vanity-delve/releases/latest/download/vanity-delve.zip",
+  "url": "https://github.com/slaguru666/vanity-delve",
+  "readme": "https://github.com/slaguru666/vanity-delve/blob/main/foundry-module/README.md"
+}