Snapshot of the cube-array textures + per-probe UBO used by the deferred
lighting pass to sample probes. Stashed on Frame.extras under
REFLECTION_PROBE_BINDINGS_KEY.
Per-probe SH diffuse coefficients (array<ShCoeffs, SHADER_MAX_PROBES>).
Present only when the feature was created with useSphericalHarmonics;
the deferred IBL_DIFFUSE_SH variant reads it for probe diffuse.
Snapshot of the cube-array textures + per-probe UBO used by the deferred lighting pass to sample probes. Stashed on Frame.extras under REFLECTION_PROBE_BINDINGS_KEY.