merge: A7 lighting (Fix A point-light shape + Fix B per-object selection) into main

Brings the worktree branch claude/thirsty-goldberg-51bb9b into main:
- aa94ced  per-vertex Gouraud + faithful calc_point_light (wrap + norm)
- 4345e77  per-OBJECT point-light selection (minimize_object_lighting)

Auto-merged cleanly against the D.2b retail-UI line (only GameWindow.cs
overlapped, resolved by git). Merged tree builds green; 35/35 Core lighting
tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -7949,6 +7949,16 @@ public sealed class GameWindow : IDisposable
             // frame — terrain, static mesh, instanced mesh, sky.
             UpdateSunFromSky(kf, playerInsideCell);
             Lighting.Tick(camPos);
+
+            // Fix B (A7 #3): build this frame's point-light snapshot and hand it to
+            // the entity dispatcher for per-OBJECT light selection
+            // (minimize_object_lighting). Replaces the single global nearest-8-to-
+            // camera UBO set for point/spot lights so a wall's torches stay tied to
+            // the wall as the camera moves. The SUN + ambient still flow through the
+            // SceneLighting UBO built below (binding=1) — terrain/sky read those.
+            Lighting.BuildPointLightSnapshot(camPos);
+            _wbDrawDispatcher?.SetSceneLights(Lighting.PointSnapshot);
+
             var ubo = AcDream.Core.Lighting.SceneLightingUbo.Build(
                 Lighting, in atmo, camPos, (float)WorldTime.DayFraction);