Fix oven batch conversion, invoice quantity, AI photo pricing, and enforce pricing flag propagation

- Carry OvenBatches/OvenCycleMinutes from Quote → Job entity (was missing fields; all job pricing recalcs hardcoded 1/null)
- Fix invoice creation from job always showing Quantity=1 (was using TotalPrice as UnitPrice with qty 1)
- Add IsAiItem to JobItem + migration; map in all 3 JobItemAssemblyService.CreateJobItem overloads so AI photo jobs no longer double-price on first edit after quote→job conversion
- Propagate IsAiItem through all existingItemsData JSON blocks in Jobs views (Edit, EditItems, Create) so the wizard preserves AI routing on re-edit
- Add PricingRoutingFlags_ExistOnBothQuoteItemAndJobItem structural test + 3 behavioral IsAiItem tests to JobItemAssemblyServiceTests
- Consolidate item wizard partials (_ItemWizardModal, _SqFtCalculatorModal) and item-wizard.css into shared locations
- Document pricing flag propagation checklist in CLAUDE.md

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

src/PowderCoating.Application/Services/JobItemAssemblyService.cs

@@ -21,6 +21,7 @@ public class JobItemAssemblyService : IJobItemAssemblyService
                 IsGenericItem = source.IsGenericItem,
                 IsLaborItem = source.IsLaborItem,
                 IsSalesItem = source.IsSalesItem,
+                IsAiItem = source.IsAiItem,
                 Sku = source.Sku,
                 ManualUnitPrice = source.ManualUnitPrice,
                 PowderCostOverride = source.PowderCostOverride,
@@ -106,6 +107,7 @@ public class JobItemAssemblyService : IJobItemAssemblyService
                 IsGenericItem = source.IsGenericItem,
                 IsLaborItem = source.IsLaborItem,
                 IsSalesItem = source.IsSalesItem,
+                IsAiItem = source.IsAiItem,
                 Sku = source.Sku,
                 ManualUnitPrice = source.ManualUnitPrice,
                 PowderCostOverride = source.PowderCostOverride,
@@ -191,6 +193,7 @@ public class JobItemAssemblyService : IJobItemAssemblyService
                 IsGenericItem = source.IsGenericItem,
                 IsLaborItem = source.IsLaborItem,
                 IsSalesItem = source.IsSalesItem,
+                IsAiItem = source.IsAiItem,
                 Sku = source.Sku,
                 ManualUnitPrice = source.ManualUnitPrice,
                 PowderCostOverride = source.PowderCostOverride,
@@ -270,6 +273,7 @@ public class JobItemAssemblyService : IJobItemAssemblyService
             IsGenericItem = seed.IsGenericItem,
             IsLaborItem = seed.IsLaborItem,
             IsSalesItem = seed.IsSalesItem,
+            IsAiItem = seed.IsAiItem,
             Sku = seed.Sku,
             ManualUnitPrice = seed.ManualUnitPrice,
             PowderCostOverride = seed.PowderCostOverride,
@@ -364,6 +368,7 @@ public class JobItemAssemblyService : IJobItemAssemblyService
         public bool IsGenericItem { get; init; }
         public bool IsLaborItem { get; init; }
         public bool IsSalesItem { get; init; }
+        public bool IsAiItem { get; init; }
         public string? Sku { get; init; }
         public decimal? ManualUnitPrice { get; init; }
         public decimal? PowderCostOverride { get; init; }