feat(registry): add Integration Definition schema v0.1

Define the open-reuse integration asset registry format with JSON Schema,
authoring template, discovery index, and analyze→classify→refactor→maintain
lifecycle documentation. Validates against the markitect-quarkdown reference
integration.

Closes OPEN-WP-0002.

registry/indexes/integrations.yaml

@@ -0,0 +1,19 @@
+version: 1
+updated: '2026-06-24'
+domain: infotech
+schema: schemas/integration.schema.yaml
+integrations:
+  - id: markitect-quarkdown
+    name: Markitect Quarkdown Render Adapter
+    status: active
+    owner: markitect-quarkdown
+    reuse_mode: adapter
+    risk_level: medium
+    path: integration/quarkdown.integration.yaml
+    repo: markitect-quarkdown
+    upstream:
+      name: Quarkdown
+      project_url: https://github.com/iamgio/quarkdown
+    notes: >
+      Reference integration for adapter reuse mode. Definition lives in the
+      consuming repository; this index row is the registry discovery surface.