feat(ui): Campaign OP slice OP6 — the Config tab

Binds the retail Options panel's Config tab (LayoutDesc 0x21000029, 27
authored rows across 6 sections) through OP2's template mechanism and
OP3's per-page OptionPage model, matching the Character/Chat tab
controllers' established pattern.

The row table is transcribed directly from two decompiled sources —
gmConfigUI::InitOptions @0x0049E400 (row order, widget shape, defaults)
and gmClient::InitUIPreferences @0x004035b0 (the complete
UIPreferences::AttachPreference registration: every label/tooltip key,
every slider's real-unit range, every menu's enum choices) — which
resolves the research docs' own "U4" unverified slider-caption pairing:
retail ships ZERO range captions on this tab (every SetSliderLabel call
passes literal string id 0).

Consumer disposition: LIVE — Sound/Ambient volume-trio sliders and their
toggle halves (AudioSettings.SfxDisabled/AmbientDisabled now gate the
already-live engine write; RuntimeSettingsController.SaveAudio newly
pushes into OpenAlAudioEngine on every change, not just at startup),
Resolution/Full Screen (immediate window resize on save). NEXT-LAUNCH
(pre-existing precedent): Sync To Refresh, Field of View. STORE-ONLY
(register rows AP-198/199/200, TS-74 extended): Sound Features/Interface
trio/Play-Only-When-Active, the nine Graphics/Rendering-Quality rows
(Vulkan has no per-feature render knobs), Camera/Input's six rows and
Use Mouse Turning (no persistent mouse-turning camera mode), Chat Font
Face/Size (distinct new fields from the existing live ChatSettings.FontSize).

AudioSettings/DisplaySettings/CameraTurningSettings/ChatSettings each
gain new fields for their slice of the 27 rows, backed by SettingsStore
round-trips. A real bug caught by testing: the scrollbar scope lookup
used the standalone-layout root id (0x100001FF), which does not survive
base-merge into the host-mounted tree — fixed to scope from the tab
host's own page-slot id (0x10000213), matching Chat's established
pattern for the same shared-scrollbar-id hazard (0x10000201, authored by
both the Chat and Config ListBoxes).

30 new tests (27 authored rows register as 30 IOptionRow instances — the
three toggle+slider trios each register two). Full Release suite:
13,107 passed / 4 skipped / 0 failed (was 13,083/4/0 — net +24, the one
existing RuntimeSettingsControllerTests case updated for SaveAudio's new
live-apply call, not a regression).

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

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

@@ -16,9 +16,19 @@ public enum ParticleRange
 
 /// <summary>
 /// Display-related preferences persisted to <c>settings.json</c>.
-/// Modern addition (no retail equivalent for FOV / vsync etc) — replaces
-/// the various <c>ACDREAM_*</c> environment variables for resolution +
-/// windowed mode with an in-game UI.
+/// Originally documented as "no retail equivalent for FOV / vsync etc" —
+/// Campaign OP slice OP6's Config-tab research corrected that: retail's
+/// <c>gmClient::InitUIPreferences @0x004035b0</c> DOES register
+/// <c>Render_FieldOfView</c> (<c>ID_Graphics_FieldOfView</c>, range
+/// [10,160]), <c>Display_SyncToRefresh</c>, <c>Display_Resolution</c>, and
+/// <c>Render_ScreenBrightness</c> (range [-1,1], mapped onto
+/// <see cref="Gamma"/> below) as genuine <c>UserPreferences.ini</c> rows —
+/// they simply had no acdream UI surface until OP6's Config tab. Resolution/
+/// Fullscreen are LIVE on save (<c>RuntimeSettingsTargets.
+/// ApplyDisplayWindowState</c> resizes the window immediately); VSync/FOV/
+/// Gamma apply at the next launch only (<c>RuntimeSettingsController.
+/// ApplyStartup</c>), matching this record's pre-existing behaviour — OP6
+/// did not change when these three take effect, only how they're reached.
 ///
 /// <para>
 /// Records are immutable; mutation goes through
@@ -34,7 +44,26 @@ public sealed record DisplaySettings(
     float Gamma,
     bool ShowFps,
     QualityPreset Quality,
-    ParticleRange ParticleRange)
+    ParticleRange ParticleRange,
+    // Campaign OP slice OP6: the Config tab's "Graphics Options" +
+    // "Rendering Quality Options" rows with no acdream renderer consumer —
+    // the world renderer is Vulkan + one aggregate QualityPreset, not
+    // per-feature knobs (register row, OP6). Persisted faithfully; every
+    // default below is retail's own byte-verified
+    // gmClient::InitUIPreferences / gmConfigUI::InitOptions literal.
+    bool AutomaticDegrades = false,
+    float GraphicsPerformance = 0f,
+    float DegradeDistance = 50f,
+    int LandscapeTextureDetail = 2,
+    int EnvironmentTextureDetail = 1,
+    int TextureFiltering = 1,
+    // UNRESOLVED (OP6, cite in register row): retail's own
+    // SetDefaultValue(8) does not index its 6-entry SetEnumChoices array
+    // (VeryLow..Extreme) — reproduced faithfully as an opaque int, not
+    // guessed into a clamped index.
+    int LandscapeDrawDistance = 8,
+    bool BuildingDetailTextures = true,
+    bool MultiPassAlpha = false)
 {
     /// <summary>Values used on first launch / when settings.json is absent.
     /// Geometry defaults preserve the pre-L.0 runtime state: Resolution