feat(chat): retail text style — two-plane glyph outlines, authored SpewBox/chat styles

Campaign CH round 4, user-gate items 1+2. Root cause: retail ships a
second (background) glyph atlas per font, dilated 2px on every side,
plus two border-pixel scalars (Font.NumHorizontalBorderPixels/
NumVerticalBorderPixels) that acdream's font reader never read — so
even the pre-existing outline parameter drew almost nothing once
enabled. Landed together (either half alone is a no-op or a
regression):

- UiDatFont carries BorderX/BorderY from the DAT font resource.
- UiRenderContext.DrawStringDat inflates the background blit's source
  and destination rect by that margin and restructures into retail's
  exact two-pass whole-string outline-then-fill model
  (UIElement_Text::DrawSelf), plus the 8-neighbour +-1px fallback for
  fonts with no background atlas. Corrects the stale "property 0xd"
  comment to the real ids, 0x21 (Outline) / 0x22 (OutlineColor).
- LayoutDesc property 0x21/0x22 import (ElementInfo.Outline/
  OutlineColor, LayoutImporter.ReadState, ElementReader.Merge/
  ApplyCanonicalLegacyProjection, DatWidgetFactory.BuildText) so every
  authored-outline element across the DAT set is correct at once.
- SpewBox: RetailFontId corrected from a round-3 heuristic
  (0x40000025) to the actually-authored 0x40000001 (18px bold serif),
  Outline=true set on the controller's UiText. Fill colour stays the
  user-gate-round-1-pinned yellow — font atlases are alpha-only
  (PFID_A8), so there is no baked shading that could explain the
  screenshot's gold as anything other than the outline itself.
- Chat transcript: default fill now seeds from its authored
  ARGB(255,204,204,204) instead of an unrelated color-table slot
  (ChatTranscriptRenderer.BuildLines takes the transcript's own
  DefaultColor as a parameter); the 34-entry LogTextType table is
  untouched, and every existing CH1 conformance test stays green
  unmodified.

Regenerated the committed chat_2100006f.json fixture from the real
installed DAT, confirming end to end (not by missing-field default)
that the transcript carries no outline.

Tests: font-reader border fields + inflation math pinned against the
real DAT font, two-pass draw ordering/tint/inflation via a new
TextRenderer.DebugSpriteSegmentVerts test seam, property 0x21/0x22
import at both the ElementReader.Merge and StateDesc-property layers,
SpewBox font/outline, and the chat default-shade seed with the color
table proven untouched.

Full Release suite: 12,610 passed / 4 skipped / 0 failed
(AcDream.slnx, complete solution).

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

tests/AcDream.App.Tests/UI/SpewBoxControllerTests.cs

@@ -252,4 +252,53 @@ public sealed class SpewBoxControllerTests
         Assert.Null(text.DatFont);
         Assert.Null(text.Font);
     }
+
+    // ── Campaign CH user-gate round 4 (2026-08-10) — font/outline AUTHORED ──
+
+    [Fact]
+    public void RetailFontId_IsTheAuthoredEighteenPixelFace_NotTheRound3Heuristic()
+    {
+        // docs/research/2026-08-10-retail-ui-text-style.md §4.2: base style
+        // 0x10000377 (the line template's own BaseElement) authors FontDID
+        // [0x40000001] directly — three independent cross-checks (FontDID,
+        // the 18px authored line height, and 4x18=72 = the authored box
+        // height) all agree. Font 0x40000025 (the round-3 "smallest
+        // confirmed-used font" heuristic) is retired.
+        Assert.Equal(0x40000001u, SpewBoxController.RetailFontId);
+    }
+
+    [Fact]
+    public void Construction_SetsOutlineTrue_MatchingTheAuthoredLineTemplate()
+    {
+        // The line template's state 0x10000002 authors property 0x21
+        // (Outline) = true with no authored 0x22 (OutlineColor), so the
+        // ctor black default applies — the heavy black border in the
+        // user's retail screenshot that earlier rounds never reproduced.
+        var root = new UiRoot { Width = 1280f, Height = 720f };
+        using var controller = new SpewBoxController(root, new SpewBoxVM(new SpewBoxState()));
+
+        UiText text = Assert.IsType<UiText>(root.Children.OfType<UiText>().Single());
+        Assert.True(text.Outline);
+        Assert.Equal(UiRenderContext.DefaultOutlineColor, text.OutlineColor);
+    }
+
+    [Fact]
+    public void Construction_WithTheAuthoredFont_LineHeightMatchesTheAuthoredEighteenPixelBox()
+    {
+        // Three-way cross-check from the class remarks: the resolved font's
+        // MaxCharHeight (18) matches the authored per-line box height (18),
+        // and 4 concurrent items x 18px = the authored 72px box height.
+        var root = new UiRoot { Width = 1280f, Height = 720f };
+        var font = new UiDatFont(
+            fgTex: 1, fgW: 64, fgH: 64,
+            bgTex: 2, bgW: 64, bgH: 64,   // background atlas present, like the real 0x40000001
+            lineHeight: 18f, baselineOffset: 14f,
+            glyphs: new Dictionary<char, FontCharDesc>());
+
+        using var controller = new SpewBoxController(
+            root, new SpewBoxVM(new SpewBoxState()), font, debugFont: null);
+
+        UiText text = Assert.IsType<UiText>(root.Children.OfType<UiText>().Single());
+        Assert.Equal(18f, text.DatFont!.LineHeight);
+    }
 }