Promote capability.wiki.engine-typed-extensions D2->D3 (architecture authored)

WikiEngineCoreArchitecture.md authored in shard-wiki + INTENT amendment ratified;
discovery D2->D3 with promotion_history. reuse-surface validate: ok. Source: SHARD-WP-0013 T5/T6.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

registry/indexes/capabilities.yaml

@@ -203,7 +203,7 @@ capabilities:
   - id: capability.wiki.engine-typed-extensions
     name: Wiki Engine with Typed Extensions
     summary: A small-core wiki engine realizing a typed-extension framework that addresses all wiki use cases and lets each shard activate only the features it needs.
-    vector: D2 / A0 / C0 / R0
+    vector: D3 / A0 / C0 / R0
     domain: helix_forge
     status: draft
     owner: shard-wiki