perf(vfx): port retail particle visibility degradation

Resolve DAT-authored particle ranges from the hardware GfxObj, apply retail distance and completed-cell visibility gates, and preserve the exact finite/infinite off-view update semantics. This removes dense-world simulation work without shortening terrain, entity, fog, or streaming distance.

Publish doorway-clipped outdoor cells through a focused frame controller, retain effect cell identity for outdoor statics, reject hidden emitters before particle-slot scans, and offer an explicit opt-in Extended particle range.

Release build succeeds and all 5,857 tests pass with five intentional skips. Retail-conformance, architecture, and adversarial review cycles are clean; connected Aerlinthe visual/performance gate pending.

Co-authored-by: OpenAI Codex <codex@openai.com>

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

@@ -3,6 +3,17 @@ using AcDream.UI.Abstractions.Settings;
 
 namespace AcDream.UI.Abstractions.Panels.Settings;
 
+/// <summary>
+/// Particle visibility distance policy. Retail uses the GfxObj-authored
+/// distance exactly; Extended is an explicit acdream adaptation for players
+/// who prefer longer-lived distant effects with the corresponding CPU cost.
+/// </summary>
+public enum ParticleRange
+{
+    Retail = 0,
+    Extended = 1,
+}
+
 /// <summary>
 /// Display-related preferences persisted to <c>settings.json</c>.
 /// Modern addition (no retail equivalent for FOV / vsync etc) — replaces
@@ -22,7 +33,8 @@ public sealed record DisplaySettings(
     float FieldOfView,
     float Gamma,
     bool ShowFps,
-    QualityPreset Quality)
+    QualityPreset Quality,
+    ParticleRange ParticleRange)
 {
     /// <summary>Values used on first launch / when settings.json is absent.
     /// Geometry/render defaults preserve the pre-L.0 runtime state — Resolution
@@ -36,7 +48,8 @@ public sealed record DisplaySettings(
         FieldOfView:  60f,
         Gamma:        1.0f,
         ShowFps:      false,
-        Quality:      QualityPreset.High);
+        Quality:      QualityPreset.High,
+        ParticleRange: ParticleRange.Retail);
 
     /// <summary>16:9 resolution presets offered in the dropdown.</summary>
     public static IReadOnlyList<string> AvailableResolutions { get; } = new[]