docs: file #400 (Credits -> gmCreditsUI, post-LA) and fix the misfiled comment

The ef96c554 batch ghosted Credits with a comment claiming it was filed
as #397 - that number is the Windows graceful-stop issue and no Credits
entry existed. #400 now records the gap properly.

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

src/AcDream.App/UI/Layout/CharacterManagementUiController.cs

@@ -134,7 +134,7 @@ internal sealed class CharacterManagementUiController : IDisposable
         // Credits (retail QueueUIMode(0x10000005) -> gmCreditsUI) is out of
         // scope this round (finding 1 note) — same "future campaign, visibly
         // ghosted, no invented action" treatment as Create above. Filed as
-        // issue #397.
+        // issue #400.
         _credits.Visible = true;
         _credits.Enabled = false;
         _credits.OnClick = null;