Add facility overhead (rent + utilities) to operating costs and pricing engine

Adds MonthlyRent, MonthlyUtilities, and MonthlyBillableHours to CompanyOperatingCosts so fixed shop occupancy costs are recovered on every quote. The pricing engine converts these into a per-hour rate and applies it as a transparent "Facility Overhead" line between oven batch cost and shop supplies. UI added in Company Settings Operating Costs tab and Setup Wizard Step 3; migration AddFacilityOverheadFields applied. Help docs and AI knowledge base updated to cover the new fields and the revised quote pricing calculation order.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Application/Mappings/CompanyProfile.cs

@@ -37,7 +37,11 @@ public class CompanyProfile : Profile
             .ForMember(dest => dest.DerivedBlastRateSqFtPerHour,
                 opt => opt.MapFrom(src => ShopCapabilityCalculator.GetBlastRateSqFtPerHour(src)))
             .ForMember(dest => dest.DerivedCoatingRateSqFtPerHour,
-                opt => opt.MapFrom(src => ShopCapabilityCalculator.GetCoatingRateSqFtPerHour(src)));
+                opt => opt.MapFrom(src => ShopCapabilityCalculator.GetCoatingRateSqFtPerHour(src)))
+            .ForMember(dest => dest.FacilityOverheadRatePerHour,
+                opt => opt.MapFrom(src => src.MonthlyBillableHours > 0
+                    ? (src.MonthlyRent + src.MonthlyUtilities) / src.MonthlyBillableHours
+                    : 0m));
         CreateMap<UpdateOperatingCostsDto, CompanyOperatingCosts>();
         CreateMap<UpdateBlastProfileDto, CompanyOperatingCosts>();