Fix invoice creation from job: discount ignored, wrong due date, wrong terms

- DueDate was computed from DefaultTurnaroundDays (a shop ops setting) instead
  of from the payment terms string; now uses PaymentTermsParser throughout
- Discount was never applied for direct jobs (PricingBreakdownJson was read for
  fees but DiscountAmount was silently skipped)
- Quote-based jobs used sourceQuote.DiscountAmount, ignoring any discount edits
  made to the job after quote conversion; now prefers the job's pricing snapshot
- Payment terms and due date now inherit from sourceQuote.Terms → customer.PaymentTerms
  → company default, so the invoice reflects the agreed or customer-specific terms
- EarlyPaymentDiscount fields now populated from inherited terms

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

src/PowderCoating.Web/Controllers/InvoicesController.cs

@@ -340,13 +340,14 @@ public class InvoicesController : Controller
             var costs = await _unitOfWork.CompanyOperatingCosts
                 .FirstOrDefaultAsync(c => c.CompanyId == currentUser.CompanyId && !c.IsDeleted);
 
+            var defaultTerms = prefs?.DefaultPaymentTerms ?? "Net 30";
             var dto = new CreateInvoiceDto
             {
                 PreparedById = currentUser.Id,
                 InvoiceDate = DateTime.Today,
-                DueDate = DateTime.Today.AddDays(prefs?.DefaultTurnaroundDays ?? 30),
+                DueDate = PaymentTermsParser.CalculateDueDate(defaultTerms, DateTime.Today),
                 TaxPercent = costs?.TaxPercent ?? 0,
-                Terms = prefs?.DefaultPaymentTerms ?? "Net 30"
+                Terms = defaultTerms
             };
 
             if (jobId.HasValue)
@@ -378,6 +379,13 @@ public class InvoicesController : Controller
                 var defaultRevenueAccount = await _unitOfWork.Accounts
                     .FirstOrDefaultAsync(a => a.AccountNumber == "4000" && a.IsActive);
 
+                // Deserialize the job's pricing snapshot up front — it is authoritative for discount,
+                // tax, and fees for both quote-based and direct jobs, because it is recalculated on
+                // every save and reflects any edits made after quote conversion.
+                QuotePricingBreakdownDto? jobBreakdown = null;
+                if (!string.IsNullOrEmpty(job.PricingBreakdownJson))
+                    jobBreakdown = JsonSerializer.Deserialize<QuotePricingBreakdownDto>(job.PricingBreakdownJson);
+
                 // If the job came from a quote, load it so we can use the agreed pricing.
                 // The quote stores the approved total including oven batch cost and shop supplies —
                 // these are quote-level charges that are NOT stored on individual job items.
@@ -461,17 +469,16 @@ public class InvoicesController : Controller
                         });
                     }
 
-                    // Use the quote's agreed tax rate and discount — not current company defaults
+                    // Use the quote's agreed tax rate. For discount, prefer the job's current pricing
+                    // snapshot — it is recalculated on every save and captures any post-conversion edits.
+                    // Fall back to the original quote discount only if no snapshot exists.
                     dto.TaxPercent     = sourceQuote.TaxPercent;
-                    dto.DiscountAmount = sourceQuote.DiscountAmount;
+                    dto.DiscountAmount = jobBreakdown?.DiscountAmount ?? sourceQuote.DiscountAmount;
                 }
                 else if (hadJobItems)
                 {
                     // Direct job — no source quote. Read all charges from the pricing snapshot so the
                     // invoice always matches the total shown on the job's Pricing Summary card.
-                    QuotePricingBreakdownDto? jobBreakdown = null;
-                    if (!string.IsNullOrEmpty(job.PricingBreakdownJson))
-                        jobBreakdown = JsonSerializer.Deserialize<QuotePricingBreakdownDto>(job.PricingBreakdownJson);
 
                     if (job.OvenBatchCost > 0.01m)
                     {
@@ -529,6 +536,22 @@ public class InvoicesController : Controller
                             RevenueAccountId = defaultRevenueAccount?.Id
                         });
                     }
+
+                    dto.DiscountAmount = jobBreakdown?.DiscountAmount ?? 0;
+                }
+
+                // Inherit payment terms from the source quote or the customer — more specific than
+                // the company-wide default set in the outer DTO. Quote terms take priority because
+                // they represent the agreed price; customer terms are next best for direct jobs.
+                var inheritedTerms = sourceQuote?.Terms ?? job.Customer?.PaymentTerms;
+                if (!string.IsNullOrWhiteSpace(inheritedTerms))
+                {
+                    dto.Terms  = inheritedTerms;
+                    dto.DueDate = PaymentTermsParser.CalculateDueDate(inheritedTerms, DateTime.Today)
+                                  ?? dto.DueDate;
+                    var (discPct, discDays) = PaymentTermsParser.ParseEarlyPaymentDiscount(inheritedTerms);
+                    dto.EarlyPaymentDiscountPercent = discPct;
+                    dto.EarlyPaymentDiscountDays    = discDays;
                 }
 
                 // Override tax to 0 for tax-exempt customers, regardless of company default or quote rate