feat(lighting): A7 visible-cell light scoping + [indoor-light] probe (NOT the #176/#177 fix)

Port retail's per-frame light collection: the point-light pool is built from ONLY the
currently-visible cells' lights, matching CObjCell::add_*_to_global_lights
(0x0052b350/0x0052b390) walked over CEnvCell::visible_cell_table (0x0052d410) — not a
flat world-space set capped at 128-nearest-camera.

- LightSource.CellId (retail insert_light arg6 -> RenderLight +0x6c); tagged at both
  registration sites from entity.ParentCellId (live weenie fixtures + dat EnvCell statics).
- LightManager.BuildPointLightSnapshot(camPos, visibleCells): a light joins the pool iff
  CellId==0 (viewer/global) or its cell is in the flood. 128 cap kept as a now-non-biting
  backstop (retail's is 40 static + 7 dynamic, 0x0081ec94/8).
- Threaded via RetailPViewDrawContext.RebuildScopedLights, invoked in DrawInside after the
  flood resolves prepareCells and before the draws (renderers select from the same
  in-place-rebuilt PointSnapshot; EnvCellRenderer clears its per-cell cache each pass).
- [indoor-light] probe (ACDREAM_PROBE_INDOOR_LIGHT=1) dumps the scoped-pool SET COMPOSITION.
  Un-skips LightManagerTests.PointSnapshot_HubScaleLightCount_ObjectSelectionIsCameraInvariant.

CORRECTION: the handoff called the camera-cap the "confirmed" #176/#177 mechanism. The probe
PROVES scoping works (291 Hub fixtures -> pool of 1-9, ~285 through-floor lights dropped/frame,
CellIds match the flood), but the user's VISUAL GATE showed BOTH symptoms unchanged. So pool
composition is NOT the cause. #176 real cause = an over-bright purple point light
(intensity=100, color 0.784,0,0.784 -- from [light-detail]); #177 = a portal-visibility miss
(stairs not drawn looking back). Both stay OPEN. This change is retail-faithful and retires the
camera-eviction latent bug; kept as such, not as the symptom fix. Register AP-85 corrected;
ISSUES #176/#177 re-diagnosed; render digest banner updated.

Decomp: insert_light 0x0054d1b0, minimize_object_lighting 0x0054d480, calc_point_light
0x0059c8b0; pseudocode docs/research/2026-07-06-a7-per-cell-lighting-pseudocode.md.
Suites green: Core 2595 + 2 skip, App 719 + 2 skip.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/AcDream.Core/Lighting/LightManager.cs

@@ -218,11 +218,33 @@ public sealed class LightManager
     /// per-object selection.
     /// </summary>
     public void BuildPointLightSnapshot(Vector3 cameraWorldPos)
+        => BuildPointLightSnapshot(cameraWorldPos, visibleCells: null);
+
+    /// <summary>
+    /// Visible-cell-scoped snapshot build — the faithful port of retail's per-frame
+    /// light collection (<c>CObjCell::add_*_to_global_lights</c> 0x0052b350/0x0052b390
+    /// walked over <c>CEnvCell::visible_cell_table</c> 0x0052d410). When
+    /// <paramref name="visibleCells"/> is non-null (an indoor root with a portal
+    /// flood), a cell-tagged light is a candidate ONLY when its <see cref="LightSource.CellId"/>
+    /// is in the visible set — a cell-less light (<c>CellId == 0</c>: the viewer fill,
+    /// global lights) is always included. This is what (a) stops an under-room light
+    /// washing THROUGH a solid floor (its cell isn't visibly flooded → excluded) and
+    /// (b) bounds the pool to the handful of visible cells so <see cref="MaxGlobalLights"/>
+    /// never evicts a visible cell's in-range light (the #176/#177 mechanism). When
+    /// <paramref name="visibleCells"/> is null (outdoor root / no flood) the behaviour
+    /// is unchanged from the legacy full-pool path.
+    /// </summary>
+    public void BuildPointLightSnapshot(Vector3 cameraWorldPos, IReadOnlySet<uint>? visibleCells)
     {
         _pointSnapshot.Clear();
         foreach (var light in _all)
         {
             if (!light.IsLit || light.Kind == LightKind.Directional) continue;
+            // Visible-cell scoping (retail add_*_lights over visible_cell_table). A
+            // cell-less light (CellId == 0: viewer fill / global) is always a candidate;
+            // a cell-tagged light joins the pool ONLY when its cell is visibly flooded.
+            if (visibleCells is not null && light.CellId != 0 && !visibleCells.Contains(light.CellId))
+                continue;
             light.DistSq = (light.WorldPosition - cameraWorldPos).LengthSquared();
             _pointSnapshot.Add(light);
         }
@@ -231,6 +253,11 @@ public sealed class LightManager
             _pointSnapshot.Sort(static (a, b) => a.DistSq.CompareTo(b.DistSq));
             _pointSnapshot.RemoveRange(MaxGlobalLights, _pointSnapshot.Count - MaxGlobalLights);
         }
+
+        // A7.L1 SET-COMPOSITION probe — only meaningful on the scoped (indoor) path.
+        // Inert unless ACDREAM_PROBE_INDOOR_LIGHT=1; the flag check keeps it zero-cost off.
+        if (visibleCells is not null && AcDream.Core.Rendering.RenderingDiagnostics.ProbeIndoorLightEnabled)
+            AcDream.Core.Rendering.RenderingDiagnostics.EmitIndoorLight(visibleCells.Count, _all, _pointSnapshot);
     }
 
     // ── Viewer light — retail SmartBox::set_viewer (0x00452c40) ──────────────