Physical lights dont match the same energy when static baked

### Tested versions v4.8.dev.custom_build [457470a8d] ### System information Ubuntu 26.4 ### Issue description When physical light units are enabled, static baked lights appear about π times brighter than the same lights rendered in real time. Both paths correctly convert the physical intensity into luminous intensity. However, real-time diffuse lighting additionally applies the normalized Lambertian BRDF factor 1/π, while the lightmapper stores its result as irradiance and does not apply this factor. When the lightmap is later multiplied by the material albedo, no further 1/π normalization occurs. As a result, identical physical lights produce different diffuse brightness depending on whether they are rendered in real time or baked as static lights. Applying 1/π to physical light energy before sending it to the lightmapper makes the baked result closely match the real-time result. Physical <img width="1078" height="770" alt="Image" src="https://github.com/user-attachments/assets/54d204cb-7b94-452e-86ef-06095fd446a4" /> Normal <img width="1078" height="770" alt="Image" src="https://github.com/user-attachments/assets/ff20df6c-9ec9-422b-9b5e-5857c53aa4b5" /> ### Steps to reproduce The project is already in physical light. Go and bake lightmap ### Minimal reproduction project (MRP) [Lightmap.zip](https://github.com/user-attachments/files/30746051/Lightmap.zip)