Fix pricing consistency across Quote → Job → Invoice; add stage-flow tests

- Store complete PricingBreakdownJson snapshot on Job at every save point so
  the Details page reads stored data rather than re-running the pricing engine
- Add 7 missing fields to Quote entity (FacilityOverheadCost, tier/quote discounts,
  SubtotalAfterDiscount) and persist them via ApplyPricingSnapshot
- Fix OvenCostId-as-rate bug in JobsController (FK was passed as decimal $/hr)
- Fix hardcoded LaborCost * 0.4 multiplier in two JobItemAssemblyService overloads
- Fix FacilityOverheadCost dropped from invoices in both quote and direct-job paths
- Fix RushFee missing from direct-job invoices (read from PricingBreakdownJson)
- Fix Notes and CatalogItemId not copied to InvoiceItem
- Add 14 unit tests in PricingStageFlowTests covering all three pricing stages

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

src/PowderCoating.Application/DTOs/Quote/QuoteDtos.cs

@@ -604,6 +604,11 @@ public class QuotePricingBreakdownDto
 
     public decimal SubtotalBeforeDiscount { get; set; }
 
+    public decimal PricingTierDiscountAmount { get; set; }
+    public decimal PricingTierDiscountPercent { get; set; }
+    public decimal QuoteDiscountAmount { get; set; }
+    public decimal QuoteDiscountPercent { get; set; }
+
     public decimal DiscountAmount { get; set; }
     public decimal DiscountPercent { get; set; }