Add archify-vscode-ext skill: Archify diagrams and models for the Archify Diagram Viewer extension

Model tasks (validate, list, scaffold, resolve), diagram tasks (validate,
render), the bundled Archify 3.0.1 runtime and yaml parser under
scripts/vendor, references for authoring, formats and folders, and the
online-shop example model.

scripts/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "archify-vscode-ext-skill-tools",
+  "private": true,
+  "type": "module",
+  "description": "Model and diagram tools for the archify-vscode-ext skill. No dependencies; Node 18+. Archify (MIT) and yaml (ISC) are vendored under vendor/.",
+  "engines": { "node": ">=18" }
+}