feat(items): port retail external-container looting

Add the ClientUISystem ground-object lifecycle, authoritative root and nested ViewContents projections, replacement and close semantics, and the DAT-authored gmExternalContainerUI strip for chests and corpses.

Route double-click loot and full or partial drag transfers through the shared retail item policy without optimistic external ownership. Remove the incorrect NoLongerViewingContents behavior from owned side packs and retire AP-106/#196.

Release build succeeds and all 5,875 tests pass with five intentional skips.

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

docs/architecture/retail-divergence-register.md

@@ -203,7 +203,6 @@ AP-94..AP-112 for the confirmed retail-UI completion gaps.
 | ~~AP-101~~ | **RETIRED 2026-07-11 (Wave 4.4e)** — toolbar control coverage is complete: DAT panel launchers, combat, Use/Examine, selected-object strip, shortcuts, and exact thrown-weapon/separate-ammo count resolution on authored element `0x10000194`. | `src/AcDream.Core/Items/ToolbarAmmoPolicy.cs`; `src/AcDream.App/UI/Layout/ToolbarController.cs` | — | — | `gmToolbarUI::UpdateAmmoID @ 0x004BF210`; `UpdateAmmoNumber @ 0x004BE9E0` |
 | AP-104 | Vitals detail element `0x100004A9` and root `HideDetail`/`ShowDetail` transitions are not wired | `src/AcDream.App/UI/Layout/VitalsController.cs` | Compact vitals values/bars are correct | Detail click does nothing and expanded retail state is unreachable | `gmVitalsUI::ListenToElementMessage @ 0x004BFC00`; `PostInit @ 0x004BFCE0` |
 | AP-105 | **PARTIAL 2026-07-13** — inherited scrollbar media/roles now come from DAT (decrement/top `0x06004C69`, increment/bottom `0x06004C6C`), and both chat backends share typed client-command routing plus one retained `ChatVM` for reply state. Retained chat still lacks complete tab/filter/unread, social availability, incoming squelch enforcement, and focus-opacity behavior. | `src/AcDream.App/UI/Layout/DatWidgetFactory.cs`; `ChatWindowController.cs`; `src/AcDream.App/UI/ClientCommandController.cs`; chat mount in `GameWindow.cs` | Shared log/send path, wrapping, scrollbar roles, command ownership, and outer maximize geometry work; later chat work consolidates the remaining presentation/filter state | Tabs are no-ops, squelched lines can still render, contextual social actions are absent, and focus visuals diverge | `gmMainChatUI @ 0x004CCCC0..0x004CE2A0`; `UIElement_Scrollbar::OnSetAttribute @ 0x004714D0`; `ChatInterface` methods |
-| AP-106 | The retained UI has no external/ground-container window lifecycle, while the original owned-side-bag `NoLongerViewingContents` premise was incorrect (#196) | `src/AcDream.App/UI`; window runtime; absent external-container controller | Owned inventory navigation remains usable and must not gain an unproven `0x0195` send; Wave 2/6 adds lifecycle ownership and the separate external surface | External container replacement/close cannot notify the server exactly once; adding the packet to owned bag close would itself diverge from the named retail call graph | `ClientUISystem.groundObject`; `CM_Inventory::Event_NoLongerViewingContents @ 0x006ABC50`; `docs/research/2026-07-10-retail-panel-behavior-pseudocode.md` |
 | ~~AP-107~~ | **RETIRED 2026-07-11 (Wave 3.3 / #197)** — typed `OfferPrimaryClick` returns `NotActive`, `ConsumedSuccess`, or `ConsumedRejected`; every retained item surface plus radar/world offers active target mode before local selection/open/use fallback. Rejections are consumed and cannot drift selection. | `src/AcDream.App/UI/ItemInteractionController.cs`; inventory/paperdoll/toolbar/radar/world call sites | — | — | `UIElement_ItemList::HandleTargetedUseLeftClick @ 0x004E24D0` |
 | AP-108 | Paperdoll/AutoWield still omit full `AutoWieldIsLegal`/dual-wield rules, double-click examine/drag from the doll, body-part selection lighting, and retail's synchronous `" - cannot unwield the %s"` failure suffix (the current send seam reports rejection asynchronously). **Primary replacement retired from this row 2026-07-14:** inventory activation and paperdoll drops share the confirmed blocker transaction, preserve explicit slot intent, relocate an already-worn item to an explicitly selected compatible slot, and emit retail's successful move-to-backpack status. **Aetheria retired 2026-07-13.** | `src/AcDream.App/UI/Layout/PaperdollController.cs`; `src/AcDream.App/UI/AutoWieldController.cs` | Basic equip slots, Aetheria, and live doll work; primary weapon, incompatible shield, and mismatched ammo blockers sequence through server-confirmed dequip→wield in both peace and war | Remaining illegal/off-hand cases, asynchronous dequip rejection wording, doll examine/drag, and selection lighting still differ functionally | `CPlayerSystem::AutoWield @ 0x00560A60`; `ACCWeenieObject::BlocksUseOfShield @ 0x0055D3E0`; `gmPaperDollUI @ 0x004A3590..0x004A5F90` |
 | AP-109 | Character Titles page is inert and live displayed-title/luminance state is absent | `src/AcDream.App/UI/Layout/CharacterStatController.cs`; `CharacterSheetProvider.cs` | Attributes/skills core output is user-accepted | Titles cannot be selected/displayed and level-200 luminance fields are missing | `gmCharacterTitleUI @ 0x0049A610`; `gmStatManagementUI::UpdateExperience @ 0x004F0A70` |