fix(render): feed look-in cells to particle and light visibility

Look-in rooms (cells reached through building portals) drew their
geometry but never entered the visible-cell set consumed by the
particle gate and the point-light candidacy scope, so their emitters
stayed frozen and their lanterns dark until the player entered or the
camera left the building. Retail has no look-in split:
ShouldDrawParticles @0x0050FE60 gates on cell->IsInView(), and a cell
installed by DrawBuilding @0x0059F2A0 -> PView::ConstructView
@0x005A57B0 is drawn by the same DrawCells traversal as any flooded
cell, so it is in view identically (per-cell in_view stamped by
PView::InitCell @0x005A4B70).

RetailPViewFrameResult now carries InViewCells (main flood + look-in
cells, the existing prepareCells union; the borrowed-scratch contract
is unchanged because RecycleLookInFrames runs at the start of the next
DrawInside). WorldSceneRenderer feeds InViewCells to
ParticleVisibilityController and the point-light scope. DrawableCells
is untouched for seals, the outside-stage predicate, diagnostics, and
the packed-product referee. The legacy 4-arg Reset defaults
InViewCells = DrawableCells for standalone callers.

User-gated 2026-08-29 at the Sanctuary Cathedral: adjacent look-in
rooms show particles and lantern lights from the root cell without
entry or an outside camera; recall/waterfall/Holtburg/paperdoll
unregressed. The pre-existing #132-family candle-behind-opening
report remains open and is unchanged by this fix.

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

src/AcDream.Core/Lighting/LightManager.cs

@@ -271,8 +271,10 @@ public sealed class LightManager
     /// geometrically closer than the player's own room's torches and win the cap,
     /// leaving the visible room dark. Scoping candidacy to the frame's actual
     /// visible cells (the render already computes this — callers pass last frame's
-    /// <c>RetailPViewFrameResult.DrawableCells</c>, one frame of latency, to avoid
-    /// re-threading a mid-render callback) removes those from contention before the
+    /// <c>RetailPViewFrameResult.InViewCells</c>, the main flood PLUS building
+    /// look-in cells, one frame of latency, to avoid re-threading a mid-render
+    /// callback; flood-only scoping darkened look-in rooms' lanterns) removes
+    /// non-visible cells from contention before the
     /// cap ever applies. The distance-sort anchor stays the PLAYER either way — this
     /// parameter only narrows candidacy, it does not change the sort (the #176
     /// correction: CAMERA anchoring, not cell scoping itself, caused the earlier