feat(D.2b): cut GameWindow over to the data-driven chat window

Replace the hand-authored chat block (UiNineSlicePanel + inline UiChatView
+ local BuildRetailChatLines/RetailChatColor statics) with
ChatWindowController.Bind(LayoutDesc 0x21000006) — the same LayoutImporter
path as the vitals window.  The controller places UiChatView (transcript) +
UiChatInput (text entry, on-submit) + UiChatScrollbar + UiChannelMenu inside
the dat-authored chrome.  The dead local statics are deleted.

Wired to _commandBus (same LiveCommandBus as the ImGui ChatPanel) so
type+Enter dispatches SendChatCmd server-ward.  Transcript keyboard set from
_uiHost.Keyboard (set by WireKeyboard above the chat block) for Ctrl+C/Ctrl+A.

Divergence register: added AD-28 (two-widget split vs UIElement_Text),
AP-38 (no in-element word-wrap), AP-39 (per-line colour vs per-glyph runs),
AP-40 (no opacity fade / shared vitalsDatFont), TS-30 (tab buttons no-op),
TS-31 (no squelch); updated IA-15 to cover both vitals + chat importer paths.

Build: 0 errors/warnings.  Tests: 392 passed, 1 skipped (expected).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/plans/2026-04-11-roadmap.md

@@ -426,6 +426,7 @@ behavior. Estimated 17–26 days focused work, 3–5 weeks calendar.
 - **✓ SHIPPED — D.2a — ImGui scaffold + `AcDream.UI.Abstractions` layer.** Shipped 2026-04-25. Wires ImGui as the short-term backend behind `ACDREAM_DEVTOOLS=1`. Defines `IPanel` / `IPanelHost` / `IPanelRenderer` / `ICommandBus` + the first ViewModel (`VitalsVM`) in the new `AcDream.UI.Abstractions` project. First real panel: `VitalsPanel` reading HP from `CombatState.GetHealthPercent`. **Backend pivoted Hexa.NET.ImGui → ImGui.NET + `Silk.NET.OpenGL.Extensions.ImGui` during integration** — Hexa's native OpenGL3 backend does its own GL function resolution via GLFW/SDL and crashed with `0xC0000005` in `ImGuiImplOpenGL3.InitNative` against Silk.NET (no GLFW/SDL present). The Silk.NET extension is purpose-built for this scenario and is the `ImGui.NET` mitigation path that `docs/plans/2026-04-24-ui-framework.md` already called out as a "one-morning operation". Stam/Mana return `float?` null in D.2a because absolute values need `LocalPlayerState` + `PlayerDescription (0x0013)` parsing (filed post-D.2a). 11 new `AcDream.UI.Abstractions.Tests` green.
 - **✓ SHIPPED — D.2b — Custom retail-look backend (Spec 1: markup engine + first panel).** Shipped 2026-06-14 (`626d06e`→`019350f`). Wired the dormant `UiHost`/`UiElement` tree into `GameWindow` (`ACDREAM_RETAIL_UI=1`) and built the **Approach-C markup engine**: `MarkupDocument` (XML → `UiElement` subtree, `{Binding}` reflection) + `ControlsIni` stylesheet loader + an `IUiRegistry` plugin UI surface (plugins ship markup + a binding, drained into the same `UiRoot`). First retail-faithful panel: a markup-driven Vitals window (`vitals.xml`) — 8-piece dat-sprite frame (`UiNineSlicePanel`) + three `UiMeter` bars (red/gold/blue + cur/max numbers) bound to `VitalsVM`, rendering live over the 3D world and coexisting with the ImGui devtools path. Retired divergence TS-30, added IA-15. Spec `docs/superpowers/specs/2026-06-14-d2b-retail-panel-frame-design.md`; plan `docs/superpowers/plans/2026-06-14-d2b-retail-panel-frame-plan.md`. NOTE the prove-out corrected two stale "facts": retail vitals are **bars not orbs**, stamina is **gold not cyan**. **Remaining: D.3 (AcFont — using the stb stopgap for now) + the glassy gradient bar sprite / brightness tune (polish); input integration (movable/clickable windows — the `UiRoot` drag/click machinery exists but isn't bridged to the Phase-K dispatcher yet); and the rest of the panels (D.5).**
 - **✓ SHIPPED — D.2b LayoutDesc importer (Plan 1 + default flip).** Plan 1 shipped 2026-06-15. *Retroactive registration — the spec requested this phase but it was not pre-registered before implementation.* Data-driven vitals window from `LayoutDesc 0x2100006C`: `LayoutImporter` resolves `BaseElement`/`BaseLayoutId` inheritance, walks the `ElementDesc` tree, and builds a live `UiElement` tree via `DatWidgetFactory` (Type 7 → `UiMeter`; all others → `UiDatElement` generic renderer). `VitalsController` binds live HP/Stamina/Mana by element id (mirrors retail `gmVitalsUI`). A/B visual gate **PASSED**: pixel-identical to the hand-authored window. **Default flip shipped 2026-06-15 (`bf77a23`):** the importer is now the default vitals window at `ACDREAM_RETAIL_UI=1`; the hand-authored `vitals.xml` and the `ACDREAM_RETAIL_UI_IMPORTER` flag were retired (`vitals.xml` recoverable from git history). The window is movable (Anchors=None + Draggable) AND horizontally resizable (Resizable/ResizeX, `8aa643f`): the dat edge-anchors reflow the pieces on width change per retail `UIElement::UpdateForParentSizeChange @0x00462640` (an earlier "fixed-size" note was wrong — inverted edge-flag reading, corrected; stretch is `RightEdge==1`). Faithful grip/dragbar-*driven* drag/resize INPUT is Plan 2. Post-flip number-render fixes (`43064ba`, `34243f2`): submission-order sprite draw (stamina/mana numbers had been overpainted by their own bars) + glyph pixel-snap (sharp at all resize widths). `MarkupDocument`/`UiNineSlicePanel` remain for the chat window + plugin panels. Spec: `docs/superpowers/specs/2026-06-15-layoutdesc-importer-design.md`; plan: `docs/superpowers/plans/2026-06-15-layoutdesc-importer.md`.
+- **✓ SHIPPED — D.2b LayoutDesc importer (Plan 2 — chat-window re-drive).** Shipped 2026-06-15. `GameWindow`'s hand-authored chat block (`UiNineSlicePanel` + inline `UiChatView`) replaced by `ChatWindowController.Bind(LayoutDesc 0x21000006, …)` — the same importer path as vitals. `ChatWindowController` places `UiChatView` (transcript) + `UiChatInput` (text entry + on-submit) + `UiChatScrollbar` (scrollbar thumb) + `UiChannelMenu` (channel selector) inside the dat-authored chrome; dead local statics `BuildRetailChatLines`/`RetailChatColor` deleted from `GameWindow` (moved into the controller). Wired to `_commandBus` (same `LiveCommandBus` as the ImGui `ChatPanel`) so type+Enter dispatches `SendChatCmd` server-ward. Transcript keyboard set from `_uiHost.Keyboard` for Ctrl+C/Ctrl+A. 392 tests green. Added divergence rows AD-28 / AP-38–40 / TS-30–31; updated IA-15.
 - **D.3 — AcFont from portal.dat.** Replace stb_truetype system font with retail `Font` DBObjs (`0x40000000..0x40000FFF`) baked from `RenderSurface` source sheets — see research slice 03 §4. Preserves retail visual identity. **(D.2b dependency — needs the custom renderer.)**
 - **✓ SHIPPED — D.4 — Dat sprites + 9-slice panel backgrounds.** Shipped 2026-06-14 with D.2b. `TextureCache.GetOrUploadRenderSurface(id, out w, out h)` decodes `RenderSurface` (`0x06xxxxxx`) **directly** (not via the Surface→SurfaceTexture chain — the prove-out finding) → GL `Texture2D`; `DrawSprite` (explicit UV-rect, per-texture batch) added to `TextRenderer` + `UiRenderContext` + a `uUseTexture=2` RGBA frag branch; `UiNineSlicePanel` composes the universal 8-piece bevel (corners `0x060074C3..C6`, edges `0x060074BF/C0/C1/C2`, center `0x06004CC2`). Remaining art polish: the glassy gradient bar fill sprite (D.2b polish).
 - **D.5 — Core panels.** Attributes (`chunk_00470000.c:FUN_0047ba70`), Skills (same), Paperdoll (`chunk_004A0000.c:FUN_004A5200`), Inventory, Spellbook (`chunk_004C0000.c`), Fellowship, Allegiance. Each uses the port sketches in slice 05. **(Targets `AcDream.UI.Abstractions` — ships with D.2a using ImGui-rendered widgets; reskinned by D.2b.)** The *chat* panel originally listed under D.5 shipped early in Phase I (I.4 input + I.7 combat translator superseded the chat-panel design here); this entry now covers Attributes / Skills / Paperdoll / Inventory / Spellbook / Fellowship / Allegiance only.