feat(D.2b): Slice 2 — paperdoll armor/non-armor partition + Slots toggle state

Adds ArmorSlotElementIds (the exact 9 ids gmPaperDollUI::ListenToElementMessage
flips per decomp 175674-175706) and PaperdollViewState (SlotView/DollVisible/
ArmorSlotsVisible/Toggle) as a nested public class on PaperdollController.

Wires ApplyView() into the constructor so the Slots button (0x100005BE) drives
armor-slot Visible and the doll viewport Visible on every click. Initial state
is doll-view (armor slots hidden). The doll viewport element (0x100001D5) is
bound as UiElement? so this slice stays independent of Slice 3's IUiViewportRenderer
seam; _armorSlots collects whichever of the 9 ids were found in the live layout.

Three new unit tests verify the id set, the default state, and the round-trip
toggle against the public PaperdollViewState surface only.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/AcDream.App.Tests/UI/Layout/PaperdollToggleTests.cs

@@ -0,0 +1,44 @@
+using AcDream.App.UI.Layout;
+using Xunit;
+
+namespace AcDream.App.Tests.UI.Layout;
+
+public class PaperdollToggleTests
+{
+    // The 9 armor element-ids that gmPaperDollUI::ListenToElementMessage flips
+    // (decomp 175674-175706). Doll-view hides these; slot-view shows them.
+    private static readonly uint[] ArmorIds =
+    {
+        0x100005abu, 0x100005acu, 0x100005adu, 0x100005aeu, 0x100005afu,
+        0x100005b0u, 0x100005b1u, 0x100005b2u, 0x100005b3u,
+    };
+
+    [Fact]
+    public void ArmorSlotIds_match_the_decomp_nine()
+    {
+        Assert.Equal(ArmorIds, PaperdollController.ArmorSlotElementIds);
+    }
+
+    [Fact]
+    public void DollView_default_shows_doll_hides_armor()
+    {
+        var v = new PaperdollController.PaperdollViewState();
+        Assert.False(v.SlotView);
+        Assert.True(v.DollVisible);
+        Assert.False(v.ArmorSlotsVisible);
+    }
+
+    [Fact]
+    public void Toggle_to_slotview_hides_doll_shows_armor_and_back()
+    {
+        var v = new PaperdollController.PaperdollViewState();
+        v.Toggle();
+        Assert.True(v.SlotView);
+        Assert.False(v.DollVisible);
+        Assert.True(v.ArmorSlotsVisible);
+        v.Toggle();
+        Assert.False(v.SlotView);
+        Assert.True(v.DollVisible);
+        Assert.False(v.ArmorSlotsVisible);
+    }
+}