refactor(runtime): own inventory transaction state

Move the retail one-request-at-a-time gate, shared use busy references, external-container state, item mana, shortcuts, and desired-component snapshots into one Runtime-owned graph over J3's exact ClientObjectTable. Retained UI and session routing now borrow that owner; reset and shutdown preserve the existing order while failure/reentrancy tests protect the transaction boundary.

Co-authored-by: Codex <codex@openai.com>

tests/AcDream.App.Tests/Composition/InteractionRetainedUiCompositionTests.cs

@@ -189,13 +189,11 @@ public sealed class InteractionRetainedUiCompositionTests
                 Combat: null!,
                 CombatAttackOperations: null!,
                 Selection: null!,
-                ExternalContainers: null!,
-                Objects: null!,
+                Inventory: null!,
                 MagicCatalog: null!,
                 Spellbook: null!,
                 Communication: null!,
                 LocalPlayer: null!,
-                ItemMana: null!,
                 StackSplitQuantity: null!,
                 UiRegistry: null,
                 CombatModeCommands: null!,
@@ -203,7 +201,6 @@ public sealed class InteractionRetainedUiCompositionTests
                 PlayerController: null!,
                 PlayerMode: null!,
                 CharacterOptions: null!,
-                Shortcuts: null!,
                 SelectionCameraFactory: static _ => Stub<SelectionCameraSource>(),
                 FrameDiagnostics: new DeferredRenderFrameDiagnosticsSource(),
                 ExistingVitals: null,