fix(overhaul): integrate reviewed room-light selection repair

Exact26 code/test/architecture/register blobs from621b41fa3; campaign ledger and lead verification included. Independent retail and production/lifetime/ABI reviews PASS. Lead69Core/176App/2actualshader pixels, viewer/clear/NaN negative controls fail as intended, exact restoration69PASS. AP68retired; AP16/35/85 residuals honest. Fresh campaign Release and graphical lighting proof still owed; temporary observer cleanup contract conditional. FPS deferred; no G4 or main merge.

docs/architecture/acdream-architecture.md

@@ -1195,6 +1195,17 @@ no reconstructed fallback. Login and portal-space retain
 last-frame point-light feedback seam are deleted. Directional shadows remain
 the next typed landscape consumer (S5-c2).
 
+Point-light retention follows retail's two independent products: seven dynamic
+and forty static candidates, with POINT lights ranked from the light owner's
+explicit root origin using stable forward insertion; SPOT/non-point lights rank
+at zero. Authored offsets affect the final light position but not the rank. The viewer light is offered to the dynamic product
+first even when its registration is late. EnvCell shells consume the complete
+47-entry product through their mode-specific binding-5 stride, while ordinary
+Gfx/building objects retain the separate eight-entry hardware selection and
+stride. Both ordinary and atmospheric mesh shaders select that stride from the
+existing lighting mode; the attenuation, ambient, packing, and per-object
+selection formulas are otherwise shared and unchanged.
+
 WorldBuilder contributes DAT decoding, mesh preparation, residency, and Vulkan
 batch mechanics only; it makes no visibility or ordering decision. Forced merge
 breaks at walk event boundaries preserve retail order while compatible draws