feat(ui): D.2b item interaction + retail cursors + live character sheet

Lands the codex-worktree D.2b stream plus the extraction the 2026-07-02
UI architecture review mandated before commit:

- ItemInteractionController: single owner of double-click use/equip/
  container-open, targeted-use mode (health kits), drag-out drop;
  toolbar shortcut drags don't drop the real item. ItemEquipRules for
  multi-slot (coat) coverage via equip masks.
- Cursor phase: CursorFeedbackController (semantic priority chain:
  drag > resize > window-move > target-mode > text) + RetailCursorCatalog
  (enums 0x27/0x28/0x29, hotspot 14,14; ClientUISystem::UpdateCursorState
  0x00564630) resolved through the portal EnumIDMap chain by
  RetailCursorResolver; RetailCursorManager applies dat cursor art to the
  OS cursor. Register row AP-72 covers the OS standard-cursor fallback.
- Character window goes live: CharacterSheetProvider owns sheet assembly,
  XP-curve/raise-cost math and the raise flow — extracted out of
  GameWindow per Code Structure Rule 1 instead of committing the ~430-line
  feature body there. Optimistic XP/credit debits go through eventful
  store APIs (new ClientObjectTable.UpdateInt64Property +
  LocalPlayerState.DebitIntProperty/DebitInt64Property) instead of raw
  property-dictionary writes; register row AP-73 covers the still-missing
  raise ledger (#163).
- RetailWindowFrame: the shared nine-slice window mount recipe; the
  character window uses it, remaining windows migrate via #164.
- Status-bar buttons toggle inventory/character windows; retail row-major
  backpack ordering; WorldSession.SendUseWithTarget + raise/train sends.

GameWindow shrinks 14,214 -> 13,877 lines despite the new features; the
sheet/raise logic is unit-tested in CharacterSheetProviderTests instead
of trapped in the god object. Build green; full suite 3,286 tests pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.App/UI/UiRoot.cs

@@ -71,6 +71,34 @@ public sealed class UiRoot : UiElement
     /// <summary>Current drag source (set between drag-begin and drop/cancel).</summary>
     public UiElement? DragSource  { get; private set; }
     public object?    DragPayload { get; private set; }
+    public bool IsWindowMoveActive => _windowDragTarget is not null;
+    public ResizeEdges ActiveResizeEdges => _resizeTarget is not null ? _resizeEdges : ResizeEdges.None;
+    public ResizeEdges HoverResizeEdges
+    {
+        get
+        {
+            var target = Pick(MouseX, MouseY);
+            var window = FindWindow(target);
+            return window is { Resizable: true }
+                ? HitEdges(window, MouseX, MouseY, ResizeGrip)
+                : ResizeEdges.None;
+        }
+    }
+    public bool HoverWindowMove
+    {
+        get
+        {
+            var target = Pick(MouseX, MouseY);
+            var window = FindWindow(target);
+            if (target is null || window is not { Draggable: true })
+                return false;
+            if (HoverResizeEdges != ResizeEdges.None)
+                return false;
+            return !target.IsDragSource
+                && !target.CapturesPointerDrag
+                && !target.HandlesClick;
+        }
+    }
     private (uint tex, int w, int h)? _dragGhost;
     /// <summary>Snapshotted drag-ghost (tex,w,h), exposed for tests. See BeginDrag.</summary>
     internal (uint tex, int w, int h)? DragGhostForTest => _dragGhost;
@@ -79,12 +107,16 @@ public sealed class UiRoot : UiElement
     private bool _dragCandidate;
     private UiElement? _windowDragTarget;
     private int _windowDragOffX, _windowDragOffY;
+    private UiElement? _lastClickTarget;
+    private long _lastClickMs;
+    private int _lastClickX, _lastClickY;
     private UiElement? _resizeTarget;
     private ResizeEdges _resizeEdges;
     private float _resizeStartX, _resizeStartY, _resizeStartW, _resizeStartH;
     private int _resizeMouseX, _resizeMouseY;
     private const int ResizeGrip = 5;   // px proximity to an edge to start a resize
     private const int DragDistanceThreshold = 3;   // pixels, retail-observed
+    private const int DoubleClickDelayMs = 500;
 
     // Hover / tooltip tracking.
     private UiElement? _hoverWidget;
@@ -106,6 +138,9 @@ public sealed class UiRoot : UiElement
     /// <summary>Raised on scroll fall-through (world zoom, etc.).</summary>
     public event Action<int /*dy*/>? WorldScrollFallThrough;
 
+    /// <summary>Raised when a drag is released over no UI element.</summary>
+    public event Action<object /*payload*/, int /*x*/, int /*y*/>? DragReleasedOutsideUi;
+
     private uint _nextEventId = 0x10000001u;
 
     public override void AddChild(UiElement child)
@@ -371,6 +406,24 @@ public sealed class UiRoot : UiElement
                                         Data0: (int)flags,
                                         Data1: (int)(x - sp.X), Data2: (int)(y - sp.Y));
                 BubbleEvent(Captured, in click);
+
+                long now = _nowMs != 0 ? _nowMs : Environment.TickCount64;
+                bool isDoubleClick =
+                    ReferenceEquals(Captured, _lastClickTarget)
+                    && now - _lastClickMs <= DoubleClickDelayMs
+                    && Math.Abs(x - _lastClickX) <= DragDistanceThreshold
+                    && Math.Abs(y - _lastClickY) <= DragDistanceThreshold;
+                if (isDoubleClick)
+                {
+                    var dbl = new UiEvent(Captured.EventId, Captured, UiEventType.DoubleClick,
+                                          Data0: (int)flags,
+                                          Data1: (int)(x - sp.X), Data2: (int)(y - sp.Y));
+                    BubbleEvent(Captured, in dbl);
+                }
+                _lastClickTarget = Captured;
+                _lastClickMs = now;
+                _lastClickX = x;
+                _lastClickY = y;
             }
             else if (btn == UiMouseButton.Right && ContainsAbsolute(Captured, x, y))
             {
@@ -504,6 +557,10 @@ public sealed class UiRoot : UiElement
         return true;
     }
 
+    /// <summary>Return the current visibility of a registered window.</summary>
+    public bool IsWindowVisible(string name)
+        => _windows.TryGetValue(name, out var w) && w.Visible;
+
     /// <summary>Flip the named window's visibility (Show if hidden, Hide if shown).
     /// Returns the new IsVisible state (false for an unknown name).</summary>
     public bool ToggleWindow(string name)
@@ -575,7 +632,10 @@ public sealed class UiRoot : UiElement
                                 Data1: (int)lx, Data2: (int)ly, Payload: DragPayload);
             t.OnEvent(in e);
         }
-        // else: dropped on nothing — no drop fires; the lift (drag-begin removal) stands (retail).
+        else if (DragPayload is { } payload)
+        {
+            DragReleasedOutsideUi?.Invoke(payload, x, y);
+        }
         DragSource = null;
         DragPayload = null;
         _dragGhost = null;