fix(chargen): Campaign CC gate round 1 closeout — Group 3: round review fixes (F4-F11, F14, F16)

The remaining code-bearing findings from the round review, F4-F16 minus
the doc-only items (batched separately):

- F4: three client-wide UiButton corpus sweeps (LabelBox path — exactly
  the 4 Town buttons, confined to chargen; conflicting custom-selection-
  pair + standard Normal/Highlight media — zero found, no gate
  tightening needed; per-state label-color map — 209 matches beyond
  chargen, confirming AP-222's mechanism has always been broadly active
  since it shipped generically in DatWidgetFactory).
- F5/F6: LayoutImporter's Batch C un-consumed-children carve-out now
  honors a child's own AuthoredInvisible flag (a narrow honor scoped to
  exactly that carve-out, not the general #408 client-wide one) — the
  chat transcript's new-text indicator (0x1000048C) was building as a
  visible phantom element retail never shows; verified both directions
  against the gold-frame pieces, which do not author Invisible.
- F7: BoundedProcessOutputCapture.AppendLine combines the line text and
  its trailing newline into one buffer and one file open/write/close
  instead of two.
- F9: corrected a stale comment in RuntimeSettingsTargets — #407 split
  DisplayModeCatalog's Resolutions/WindowedResolutions in two, so the
  fullscreen validator's own narrower list is now DELIBERATELY different
  from the Config dropdown's fuller offering, not the "must match" bug
  the comment described.
- F10: documented (not changed) why the LabelBox path's default 3px
  inset and the face-relative +4px gap in DatWidgetFactory.BuildButton
  are deliberately different numbers — neither carries a retail
  citation, and moving either to match the other would be an unfounded
  guess on a button that currently works correctly.
- F11: Heritage/Profession/Summary/Town description pages now compose
  DatRichText.Compose's result ONCE inside their already revision-gated
  Refresh, caching the built line list instead of re-wrapping on every
  draw call.
- F14: documented (not changed) why PrivateEntityViewportRenderer's
  _animatedIds set carrying a reserved-but-never-drawn backdrop id is
  harmless — BuildDrawEntities already excludes a null/empty backdrop
  from the actual draw list, so the id is never looked up.
- F16: the Summary preview now uses its own render-id pair
  (SummaryPreviewRenderId/SummaryPreviewBackdropRenderId, 0xDA11D035/
  0xDA11D036) instead of sharing the Appearance page's
  (0xDA11D032/0xDA11D034) — confirmed by tracing
  FixedEntityTextureOwnerLease through TextureCache to
  CompositeTextureArrayCache's shared owner tracker that both pages'
  previews share ONE process-wide TextureCache, so sharing render ids
  was a real cross-page texture-release collision (either page's own
  re-dress or disposal could release the OTHER page's still-active
  textures), not a theoretical one.

F3's own register bookkeeping (AP-229 addendum) and F12's register/AD
header-count corrections land in the docs-only commit alongside F15.

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

src/AcDream.Launcher.Core/Launching/BoundedProcessOutputCapture.cs

@@ -99,7 +99,18 @@ public sealed class BoundedProcessOutputCapture : IDisposable
     /// <c>Process.ErrorDataReceived</c> line) followed by a newline. Never
     /// throws. A <see langword="null"/> line (the sentinel .NET's
     /// <c>ErrorDataReceived</c> raises once when the stream closes) is a
-    /// silent no-op.</summary>
+    /// silent no-op.
+    ///
+    /// <para>
+    /// F7 (Campaign CC gate round 1 closeout): the text and its trailing
+    /// newline are combined into ONE buffer and written through ONE
+    /// <see cref="AppendLocked"/> call. The class doc's own "every write
+    /// opens the file fresh" contract means two separate calls (text, then
+    /// newline) used to open/write/flush/close the file TWICE per logical
+    /// line — needless I/O for a sink that already fires once per received
+    /// output line.
+    /// </para>
+    /// </summary>
     public void AppendLine(string? line)
     {
         if (line is null)
@@ -107,10 +118,14 @@ public sealed class BoundedProcessOutputCapture : IDisposable
             return;
         }
 
+        byte[] textBytes = Encoding.UTF8.GetBytes(line);
+        var buffer = new byte[textBytes.Length + Newline.Length];
+        textBytes.CopyTo(buffer, 0);
+        Newline.CopyTo(buffer, textBytes.Length);
+
         lock (_gate)
         {
-            AppendLocked(Encoding.UTF8.GetBytes(line));
-            AppendLocked(Newline);
+            AppendLocked(buffer);
         }
     }