docs: OP6 re-review CLOSED — slice code-complete, gate ready; doc residuals

The re-reviewer byte-decoded ALL six caption sites independently (no
transposition; a third evidence line from the fixture's authored
left/right label geometry), re-verified the audio chain through the one
place an inversion could still hide (the checkbox pass-throughs), and
hand-traced the 97-key conformance table (exactly 97, none invented or
dropped). Residuals applied here: SF-1 the AudioSettings doc comment's
wrong function attribution (the SetDefaultValue literals live in
gmConfigUI::InitOptions @0x0049E435/E457/E479, not InitUIPreferences);
SF-2 the gate script no longer asserts an unread DAT caption — it gates
on behaviour and asks the tester to report the authored English
verbatim; lane A's stale '24 option rows' corrected to 27 (the 39-item
pin is the authoritative tally). AudioSettings.cs change is
comment-only (no executable-code delta; suite state carries from
67b0815c, re-verified at the next code commit).

Campaign state: OP1-OP7 ALL CODE-COMPLETE; OP3/OP4/OP5/OP6 gates ready;
OP8 (Configure Keyboard) is the sole remaining implementation slice.

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

src/AcDream.UI.Abstractions/Panels/Settings/AudioSettings.cs

@@ -103,7 +103,10 @@ public sealed record AudioSettings(
     /// sound preference (<c>SoundManager::InitPrefs</c> @ <c>0x005503F0</c>),
     /// so ambient starts at unity rather than the invented 0.8. The six OP6
     /// trailing fields default to retail's OWN byte-verified
-    /// <c>gmClient::InitUIPreferences</c> literals: <c>SetDefaultValue(1,
+    /// <c>gmConfigUI::InitOptions</c> literals (@0x0049E435/E457/E479 —
+    /// OP6 re-review SF-1: an earlier revision mis-attributed these to
+    /// <c>gmClient::InitUIPreferences</c>, which contains no
+    /// <c>SetDefaultValue</c> at all): <c>SetDefaultValue(1,
     /// 0x3f800000)</c> on every trio (toggle=checked=enabled per the class
     /// doc's byte evidence, slider=1.0) — retail's 2013 EoR build genuinely
     /// ships every Sound category ENABLED and audible by default; ported