fix(chat): CH2 re-review nits — resize centering, top-aligned flow, sweep wording

Applies the seven NITs from the CH2 re-review (verdict APPROVE-WITH-FIXES,
following the REJECT->rework at e0e78883):

1. SpewBoxController's centered Left was captured once via
   AnchorEdges.Top and replayed forever on resize (UiElement.ApplyAnchor's
   Left/Right-both-false branch pins a fixed margin). Anchors is now
   AnchorEdges.None and Tick recomputes Left every frame against the
   current root width.

2. OneLine=false was defaulting to UiText's bottom-pinned transcript flow
   (VerticalJustify honored only via ConfigureDatState, which this
   synthesized element never calls). Added UiText.HonorVerticalJustification
   so a non-DAT controller can opt the scrollable path into
   VerticalJustify without a full LayoutDesc binding; SpewBoxController
   sets VerticalJustify=Top so lines flow from the top of the 450x72 box,
   matching newest-at-top insert semantics. Noted as invented-pending-
   measurement in AP-178's row (no new row).

3. Documented the deliberate inversion of UiText.LinesProvider's
   oldest-first contract in SpewBoxController.Tick (SpewBoxVM.Lines feeds
   newest-first, which is correct specifically because the box is now
   top-aligned) and added a test pinning the rendered order (newer message
   is the topmost line), driving root.Tick.

4. Fixed the stale "retail's code default, 1" comment in
   SpewBoxControllerTests — MaxConcurrentItems is the shipped LayoutDesc's
   AUTHORED value, 4.

5. Added the matching unmapped-id diagnostics line to
   LiveSessionRuntimeFactory's ShowWeenieError sink, matching the pattern
   GameEventWiring's WeenieError/WeenieErrorWithString handlers already
   use.

6. Corrected the "EXHAUSTIVE Portal sweep found ZERO" overclaim in
   SpewBoxLayoutDumpDiagnostic: the loop's id source was DatCollection's
   top-level aggregate GetAllIdsOfType<LayoutDesc>(), not dats.Portal's
   own (which reports a count of ZERO for this type), so querying those
   ids against dats.Portal.TryGet established nothing about Portal either
   way. Corrected the same overclaim echoed in SpewBoxState's
   MaxConcurrentItems doc comment and in AP-178's register text (both the
   table row and the section-header history line). What's actually
   established: dats.Local hosts the SpewBox layout at 0x21000011; whether
   Portal also carries a copy remains unestablished.

7. Added a test exercising the full ShowWeenieError -> AddText -> SpewBox
   path for id 0x0561 (the 50-friends-cap refusal) in
   LiveSessionCommandRouterTests, mirroring LiveSessionRuntimeFactory's
   ShowWeenieError closure exactly since every other LiveSessionRuntimeFactory
   test in this tree is a source-text conformance grep, not an
   instantiation.

Ledger: CH2 ledger row's review column now reads REJECT -> reworked
e0e78883 -> re-review APPROVE-WITH-FIXES -> nits (this commit); Status
header flips CH2 to code-complete/closed pending the user gate, CH3 next.

Build green; touched-project tests green (19/19 new/changed,
4351/3354 App.Tests unaffected pass); full Release suite 11,916 passed /
4 skipped / 0 failed (baseline 11,914/4/0 plus the two new tests this
commit adds).

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

src/AcDream.App/UI/SpewBoxController.cs

@@ -1,4 +1,5 @@
 using System.Numerics;
+using AcDream.App.UI.Layout;
 using AcDream.UI.Abstractions.Panels.SpewBox;
 
 namespace AcDream.App.UI;
@@ -83,11 +84,23 @@ internal sealed class SpewBoxController : IDisposable
     /// (<c>leftEdge=3</c>/<c>rightEdge=3</c>, "centered" per
     /// <c>ElementReader.ToAnchors</c>'s doc comment) mean the box is a
     /// FIXED-width block horizontally centered in its parent, not a
-    /// full-viewport stretch — the constructor below anchors it that way
-    /// (a one-time centered <see cref="UiText.Left"/> computed against
-    /// <see cref="UiRoot.Width"/>, <see cref="AnchorEdges.Top"/> only) since
-    /// <see cref="AnchorEdges"/> has no "centered, fixed-width" flag
-    /// combination to express retail's mode 3 directly.
+    /// full-viewport stretch. <see cref="AnchorEdges"/> has no "centered,
+    /// fixed-width" flag combination to express retail's mode 3 directly, so
+    /// <see cref="Tick"/> recomputes a centered <see cref="UiText.Left"/>
+    /// against the CURRENT <see cref="UiRoot.Width"/> every frame instead of
+    /// anchoring.
+    /// <para>
+    /// CH2 re-review nit 1
+    /// (<c>docs/plans/2026-08-09-chat-parity-campaign.md</c>): the original
+    /// rework anchored with <see cref="AnchorEdges.Top"/> only, meaning
+    /// <see cref="UiElement.ApplyAnchor"/> captured the constructor's
+    /// one-time centered <c>Left</c> as a fixed left MARGIN
+    /// (<c>ComputeAnchoredRect</c>'s Left/Right-both-false branch) and
+    /// replayed that absolute pixel position forever — a window resize left
+    /// the box off-center. <see cref="Anchors"/> is now
+    /// <see cref="AnchorEdges.None"/> (so <c>ApplyAnchor</c> is a no-op) and
+    /// centering is owned entirely by the per-frame recompute below.
+    /// </para>
     /// </summary>
     private const float SpewBoxWidth = 450f;
     private const float SpewBoxHeight = 72f;
@@ -127,17 +140,32 @@ internal sealed class SpewBoxController : IDisposable
             Name = "SpewBox",
             // Centered fixed-width block (retail's "mode 3" edge code on
             // both left and right) — see the AP-178 extent comment above.
+            // This is only the FIRST frame's value; Tick recomputes it
+            // every frame against the current root width (CH2 re-review
+            // nit 1 — see the extent comment's nit-1 paragraph).
             Left = (root.Width - SpewBoxWidth) / 2f,
             Top = TopOffset,
             Width = SpewBoxWidth,
             Height = SpewBoxHeight,
-            Anchors = AnchorEdges.Top,
+            Anchors = AnchorEdges.None,
             Centered = true,
             // AUTHORED MaxConcurrentItems is 4, not retail's code-default 1
             // (see SpewBoxState.MaxConcurrentItems) — OneLine=true would
             // silently collapse the box back down to showing only the
             // newest of up to 4 concurrent lines.
             OneLine = false,
+            // CH2 re-review nit 2 (docs/plans/2026-08-09-chat-parity-campaign.md):
+            // retail's own authored vertical justification for THIS element
+            // is unknown (register row AP-178 covers presentation
+            // unknowns) — top-aligned flow is acdream's own choice, made
+            // because it is the only placement consistent with "lines flow
+            // from the top, newest on top" (see Tick's ordering comment).
+            // HonorVerticalJustification opts the scrollable multi-line
+            // path into VerticalJustify without a full ConfigureDatState
+            // LayoutDesc binding, which this synthesized element does not
+            // have.
+            VerticalJustify = VJustify.Top,
+            HonorVerticalJustification = true,
             ClickThrough = true,
             ZOrder = int.MaxValue,
             DefaultColor = SpewBoxColor,
@@ -166,10 +194,29 @@ internal sealed class SpewBoxController : IDisposable
     /// </param>
     private void Tick(double nowSeconds)
     {
-        // SpewBoxVM.Lines returns newest-first, matching retail's
-        // InsertItem(item, 0) — with OneLine now false and the AUTHORED
-        // MaxConcurrentItems == 4 (see SpewBoxState.MaxConcurrentItems),
-        // up to 4 lines render, newest on top.
+        // CH2 re-review nit 1 (docs/plans/2026-08-09-chat-parity-campaign.md):
+        // Anchors is AnchorEdges.None (see the AP-178 extent comment on
+        // SpewBoxWidth), so nothing else recenters this element on a
+        // window resize — recompute every frame against the CURRENT root
+        // width rather than the width captured once at construction.
+        _text.Left = (_root.Width - SpewBoxWidth) / 2f;
+
+        // CH2 re-review nit 3 (docs/plans/2026-08-09-chat-parity-campaign.md):
+        // deliberate inversion of UiText.LinesProvider's documented
+        // contract ("Provider of the lines to show, oldest-first" —
+        // UiText.cs). SpewBoxVM.Lines returns newest-first, matching
+        // retail's InsertItem(item, 0), and this controller feeds that
+        // order straight through WITHOUT reversing it. That is correct
+        // here specifically because the box is top-aligned
+        // (VerticalJustify.Top + HonorVerticalJustification above): index 0
+        // of the lines array draws at the TOP of the box, so feeding
+        // newest-first into a slot documented as oldest-first is exactly
+        // what makes "newest line on top" true. Reversing the feed to
+        // satisfy the doc comment literally would flip the visible order to
+        // oldest-on-top, which is wrong for this element — see
+        // SpewBoxControllerTests' rendered-order test. With OneLine now
+        // false and the AUTHORED MaxConcurrentItems == 4 (see
+        // SpewBoxState.MaxConcurrentItems), up to 4 lines render.
         IReadOnlyList<SpewBoxLine> lines = _vm.Lines(nowSeconds);
         _text.Visible = lines.Count > 0;
         if (lines.Count == 0)