Add oven batch cost to AI Quick Quote (1 batch, DefaultOvenCycleMinutes or 50 min)

Previously the quick quote omitted the oven charge entirely, so saved quotes
were under-priced relative to full quotes from the same items.

Pricing: CalculatePricing now calculates ovenBatchCost = (cycleMin/60) × OvenOperatingCostPerHour
using DefaultOvenCycleMinutes (fallback 50 min), then adds it to the total as a quote-level
charge matching how PricingCalculationService handles oven costs.

Save path: SaveQuickQuoteRequest gains OvenBatchCost + OvenCycleMinutes; the Quote record
now stores OvenBatchCost, OvenCycleMinutes, and Total = ItemsSubtotal + OvenBatchCost.

Display: results card shows a sub-line under the estimate price:
"incl. oven 1 batch 50 min: $12.00"

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

src/PowderCoating.Web/Views/Shared/_AiQuickQuoteWidget.cshtml

@@ -86,6 +86,7 @@
                         <div>
                             <div class="small text-muted">Estimate</div>
                             <div class="fs-5 fw-bold text-success" id="qq-res-price"></div>
+                            <div id="qq-res-oven" class="text-muted" style="font-size:0.73rem;"></div>
                         </div>
                         <div class="text-end">
                             <div class="small text-muted">Confidence</div>