Fix 'Oven (1 batch × 0 min)' display when OvenCycleMinutes is null

Quote.OvenCycleMinutes is nullable — null means 'use company default'.
The Details and DownloadPdf actions were converting null → 0 before passing
it to the view, so the pricing summary showed '× 0 min' even though the
oven cost was correctly calculated from DefaultOvenCycleMinutes.

Fix: resolve null against operatingCosts.DefaultOvenCycleMinutes in both
controller actions (DownloadPdf now loads operating costs for this). Added
a defensive > 0 guard in the view so the minutes clause is omitted entirely
if it still comes through as 0.

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

src/PowderCoating.Web/Controllers/QuotesController.cs

@@ -365,6 +365,8 @@ public class QuotesController : Controller
             }
 
             // Build pricing breakdown from stored snapshot values — never recalculate on load
+            // OvenCycleMinutes null means "use company default"; resolve it here so the view
+            // never displays "× 0 min" when the oven was priced against DefaultOvenCycleMinutes.
             quoteDto.PricingBreakdown = new QuotePricingBreakdownDto
             {
                 MaterialCosts           = quote.MaterialCosts,
@@ -373,7 +375,7 @@ public class QuotesController : Controller
                 ItemsSubtotal           = quote.ItemsSubtotal,
                 OvenBatchCost           = quote.OvenBatchCost,
                 OvenBatches             = quote.OvenBatches,
-                OvenCycleMinutes        = quote.OvenCycleMinutes ?? 0,
+                OvenCycleMinutes        = quote.OvenCycleMinutes ?? operatingCosts?.DefaultOvenCycleMinutes ?? 0,
                 ShopSuppliesAmount      = quote.ShopSuppliesAmount,
                 ShopSuppliesPercent     = quote.ShopSuppliesPercent,
                 OverheadCosts           = quote.OverheadAmount,
@@ -539,6 +541,9 @@ public class QuotesController : Controller
 
             // Get company info and logo
             var currentUser = await _userManager.GetUserAsync(User);
+            var pdfOperatingCosts = currentUser != null
+                ? await _pricingService.GetOperatingCostsAsync(currentUser.CompanyId)
+                : null;
 
             // Populate pricing breakdown from stored snapshot values — never recalculate on load
             quoteDto.PricingBreakdown = new QuotePricingBreakdownDto
@@ -549,7 +554,7 @@ public class QuotesController : Controller
                 ItemsSubtotal           = quote.ItemsSubtotal,
                 OvenBatchCost           = quote.OvenBatchCost,
                 OvenBatches             = quote.OvenBatches,
-                OvenCycleMinutes        = quote.OvenCycleMinutes ?? 0,
+                OvenCycleMinutes        = quote.OvenCycleMinutes ?? pdfOperatingCosts?.DefaultOvenCycleMinutes ?? 0,
                 ShopSuppliesAmount      = quote.ShopSuppliesAmount,
                 ShopSuppliesPercent     = quote.ShopSuppliesPercent,
                 OverheadCosts           = quote.OverheadAmount,