feat(plugins): complete Campaign LA5 cross-host hosting

docs/architecture/acdream-architecture.md

@@ -120,7 +120,16 @@ handlers and controllers translate those intents to `WorldSession`; panels
 never inspect or construct wire messages.
 Plugins register retained gameplay markup through the BCL-only
 `AcDream.Plugin.Abstractions.IUiRegistry`; they do not import App or
-presentation assemblies. Core `SelectionState` is the sole selected-object owner for world,
+presentation assemblies. `IPluginHost.HasUi` is the explicit capability edge:
+the graphical host supplies its retained registry, while no-window hosts
+return `false` and the BCL-only `NoOpUiRegistry`, which retains no plugin
+binding. Both hosts use Core's session-scoped discovery/lifetime orchestrator
+and the same config allow-list semantics (absent loads all; explicit empty
+loads none). The headless adapter projects entity snapshots on demand from the
+canonical Runtime view, subscribes to Runtime's ordered events, and borrows the
+exact Runtime selection owner; it does not mirror gameplay state.
+
+Core `SelectionState` is the sole selected-object owner for world,
 radar, inventory, paperdoll, toolbar, use/examine consumers, and plugins;
 `IPluginHost.Selection` exposes that same state and retail-style old/new callback.
 Temporary pointer modes are separate App orchestration in `InteractionState` and
@@ -174,6 +183,9 @@ parallel window-lifecycle map.
 ```
 src/
   AcDream.Core/              Layer 2-4: no Vulkan, no Silk.NET, pure logic
+    Plugins/
+      PluginSession.cs        -> shared per-host allow-list, failure isolation,
+                                 status outcome, and collectible ALC lifetime
     Physics/
       PhysicsBody.cs          -> body state / integration foundation (done)
       CollisionPrimitives.cs  -> retail primitive helpers (partial, active)
@@ -288,6 +300,8 @@ src/
     Configuration/           -> strict versioned process/session config
     Credentials/             -> redacted env/stdin/owner-only-file providers
     Hosting/                 -> one GameRuntime/session/lease/policy lifetime
+    Plugins/                 -> no-window IPluginHost borrowing Runtime/Core;
+                                BCL no-op UI and per-session plugin lifetime
     Policies/                -> typed Runtime-view/command consumers
     -> references Runtime only; no presentation/backend package
     -> Slice K complete: portable single/multi-session production host,
@@ -298,6 +312,7 @@ src/
   AcDream.Plugin.Abstractions/  Layer 5: plugin interfaces
     IAcDreamPlugin.cs         -> done
     IPluginHost.cs            -> done
+    IUiRegistry.cs            -> capability-aware retained/no-op UI contract
     IGameState.cs             -> done
     IEvents.cs                -> done
     ISelectionService.cs      -> done
@@ -352,6 +367,7 @@ src/
       PlayerMovementController.cs  -> active movement driver
     Plugins/
       AppPluginHost.cs        -> done
+      GraphicalPluginSession.cs -> thin shared-session/root/status adapter
 ```
 
 The 4B2 production SetPosition routes and shared local-controller body remain