fix(ui,runtime): Campaign LA gate-round-2 batch-review fixes F1,F3-F8; file #401

F1 (MUST-FIX): RetailWaitDialogView was the ONE dialog view the 0a7dc7d6
EffectiveCanvasSize sweep missed - the Entering World wait dialog (fires
on ENTER, the char screen primary action) still centered against the raw
window and landed off the visible canvas. Same three-line fix as its three
siblings; the enter-wait test now grows the window over the fixed canvas
and asserts canvas-space centering.

F3/F4: two stale assertions about the DELETED first AD-98 substitution
(the register section-2 header line and the live-DAT oracle test doc) now
describe the completed FixedCanvasSize mechanism - the C4-closeout failure
mode, caught before it cost anything.

F5: RetailDialogData.Confirmation sets ElementAttribute40 itself (retail
MakeConfirmExitDialog writes 0x8E=1, 0xAC=1, 0xC5); the manual set in
GameplayConfirmationController is gone.

F6: MapWindowToCanvas truncates instead of rounding - rounding mapped the
window far edge one past the canvas last valid coordinate, a 1px dead
hit-test band; test updated to truncation semantics + far-edge case.

F7: AD-98 records that the no-letterbox aspect claim has no decomp
citation and is confirmed by the user live gate pass 2026-08-15.

F8: the durable world-name read in StartCore is IsCurrent-gated like every
neighbouring step.

F2 filed as #401 (invert RetailUi to opt-out - product-default decision,
not a gate fix).

App 5100+6 skips, Runtime 1666, green.

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

src/AcDream.App/UI/UiRoot.cs

@@ -65,10 +65,14 @@ public sealed class UiRoot : UiElement
 
     private (int x, int y) MapWindowToCanvas(int x, int y)
     {
+        // Truncate, not round (batch review F6): rounding maps the window's
+        // last column/row one past the canvas's last valid coordinate
+        // (1919/2.4 → 800, past 799), creating a 1px dead band at the far
+        // right/bottom edge. Truncation maps 0..1919 onto 0..799 exactly.
         Vector2 scale = CanvasScale;
         return scale == Vector2.One
             ? (x, y)
-            : ((int)MathF.Round(x / scale.X), (int)MathF.Round(y / scale.Y));
+            : ((int)(x / scale.X), (int)(y / scale.Y));
     }
 
     // ── Device-level state ───────────────────────────────────────────────