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/Wizard/WizardDtos.cs

@@ -112,6 +112,19 @@ public class WizardStep2Dto
 
     [Display(Name = "Shop Capability Tier")]
     public ShopCapabilityTier ShopCapabilityTier { get; set; } = ShopCapabilityTier.Small;
+
+    // Facility Overhead
+    [Range(0, 1000000)]
+    [Display(Name = "Monthly Rent ($)")]
+    public decimal MonthlyRent { get; set; } = 0m;
+
+    [Range(0, 1000000)]
+    [Display(Name = "Monthly Utilities ($)")]
+    public decimal MonthlyUtilities { get; set; } = 0m;
+
+    [Range(1, 10000)]
+    [Display(Name = "Billable Hours/Month")]
+    public int MonthlyBillableHours { get; set; } = 160;
 }
 
 // ─── Step 3: Branding & Numbering ───────────────────────────────────────────