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/yaml/schema/common/seq.js

@@ -0,0 +1,17 @@
+import { isSeq } from '../../nodes/identity.js';
+import { YAMLSeq } from '../../nodes/YAMLSeq.js';
+
+const seq = {
+    collection: 'seq',
+    default: true,
+    nodeClass: YAMLSeq,
+    tag: 'tag:yaml.org,2002:seq',
+    resolve(seq, onError) {
+        if (!isSeq(seq))
+            onError('Expected a sequence for this tag');
+        return seq;
+    },
+    createNode: (schema, obj, ctx) => YAMLSeq.from(schema, obj, ctx)
+};
+
+export { seq };