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/vendor/archify.json

@@ -0,0 +1,6 @@
+{
+  "upstream": "https://github.com/tt-a1i/archify",
+  "license": "MIT",
+  "version": "3.0.1",
+  "revision": "7158026e852f3aa6578c741e673b46d7878c92c1"
+}