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/DTOs/Company/CompanySettingsDtos.cs

@@ -140,6 +140,14 @@ namespace PowderCoating.Application.DTOs.Company
         public decimal DerivedBlastRateSqFtPerHour { get; set; }
         /// <summary>Derived coating rate — shown to the user as a sanity-check value.</summary>
         public decimal DerivedCoatingRateSqFtPerHour { get; set; }
+
+        // Facility Overhead
+        public decimal MonthlyRent { get; set; }
+        public decimal MonthlyUtilities { get; set; }
+        public int MonthlyBillableHours { get; set; } = 160;
+
+        /// <summary>Derived facility overhead rate = (MonthlyRent + MonthlyUtilities) / MonthlyBillableHours.</summary>
+        public decimal FacilityOverheadRatePerHour { get; set; }
     }
 
     /// <summary>
@@ -228,6 +236,19 @@ namespace PowderCoating.Application.DTOs.Company
 
         [Range(0, 500)]
         public decimal ComplexityExtremePercent { get; set; } = 25m;
+
+        // Facility Overhead
+        [Range(0, 1000000, ErrorMessage = "Monthly rent must be between 0 and 1,000,000")]
+        [Display(Name = "Monthly Rent ($)")]
+        public decimal MonthlyRent { get; set; } = 0m;
+
+        [Range(0, 1000000, ErrorMessage = "Monthly utilities must be between 0 and 1,000,000")]
+        [Display(Name = "Monthly Utilities ($)")]
+        public decimal MonthlyUtilities { get; set; } = 0m;
+
+        [Range(1, 10000, ErrorMessage = "Billable hours must be between 1 and 10,000")]
+        [Display(Name = "Billable Hours/Month")]
+        public int MonthlyBillableHours { get; set; } = 160;
     }
 
     /// <summary>DTO for updating the company AI profile text used for AI Photo Quote calibration.</summary>