research: write up wiki-engines landscape scan; send IAM demand to netkingdom

- Add README.md + findings.md to research/260608-wikiengines-overview/ to
  match sibling research convention (was a bare Perplexity dump). findings.md
  synthesizes the engine landscape into adapter-contract implications and maps
  to INTENT (capability heterogeneity, L0->L4 ladder, backend-neutrality).
- Mark the netkingdom integration demand as sent: capability request
  3136a9e2 (auto-routed to netkingdom) + inbox message 46c60f17.

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

demand/260608-netkingdom-integration-requirements.md

@@ -82,8 +82,10 @@ shard-wiki authorizes; it never authenticates or stores identity. Everything bel
 
 ## Next actions
 
-- [ ] Send this as a **capability request / interface negotiation** to the netkingdom domain
-      (user-engine + net-kingdom owners) via the state hub.
+- [x] Send this as a **capability request / interface negotiation** to the netkingdom domain
+      (user-engine + net-kingdom owners) via the state hub. — *sent 2026-06-13, capability
+      request `3136a9e2-0c1a-4b3f-8a02-ef47b27071fe` (auto-routed to `netkingdom`), inbox
+      message `46c60f17`.*
 - [ ] Lock the **token claim contract** (A2–A4) and the **membership read API** (B1–B5) first
       — they gate everything L2+.
 - [ ] Define shard-wiki's **audit event schema** (C1) against user-engine's existing audit model.