Add platform powder catalog management UI with full CRUD and AI lookup

- PowderCatalogController: Create, Edit, ToggleDiscontinued actions; searchable/filterable/sortable Index with pagination; AiLookup and AiAugmentFromUrl endpoints backed by IInventoryAiLookupService
- New views: Create, Edit, _Form partial (with AI-assisted field population), overhauled Index grid with completeness quality badges and responsive mobile cards
- New ViewModels: PowderCatalogIndexViewModel, PowderCatalogFormViewModel, PowderCatalogListItemViewModel
- AI lookup improvements: SpecificGravity field added to InventoryAiLookupResult; ApplyPowderFallbacks derives CoverageSqFtPerLb from specific gravity when docs omit it; DefaultTransferEfficiency (65%) applied everywhere transfer efficiency is null
- powder-catalog-ai-lookup.js: client-side AI lookup and URL augment wiring for the catalog form

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

src/PowderCoating.Web/Controllers/InventoryController.cs

@@ -20,6 +20,8 @@ namespace PowderCoating.Web.Controllers;
 [Authorize(Policy = AppConstants.Policies.CanManageInventory)]
 public class InventoryController : Controller
 {
+    private const decimal DefaultTransferEfficiency = 65m;
+
     private readonly IUnitOfWork _unitOfWork;
     private readonly IMapper _mapper;
     private readonly ILogger<InventoryController> _logger;
@@ -745,7 +747,7 @@ public class InventoryController : Controller
             if (match.ColorFamilies      != null) result.ColorFamilies      = match.ColorFamilies;
             if (match.RequiresClearCoat  != null) result.RequiresClearCoat  = match.RequiresClearCoat;
             if (match.CoverageSqFtPerLb  != null) result.CoverageSqFtPerLb  = match.CoverageSqFtPerLb;
-            if (match.TransferEfficiency != null) result.TransferEfficiency = match.TransferEfficiency;
+            result.TransferEfficiency ??= GetEffectiveTransferEfficiency(match.TransferEfficiency);
             // URL / price fields: fill gaps only — AI may have found something better
             result.ImageUrl    ??= match.ImageUrl;
             result.SpecPageUrl ??= match.ProductUrl;
@@ -775,7 +777,7 @@ public class InventoryController : Controller
                 ColorFamilies      = result.ColorFamilies,
                 RequiresClearCoat  = result.RequiresClearCoat,
                 CoverageSqFtPerLb  = result.CoverageSqFtPerLb,
-                TransferEfficiency = result.TransferEfficiency,
+                TransferEfficiency = GetEffectiveTransferEfficiency(result.TransferEfficiency),
                 ImageUrl           = result.ImageUrl,
                 ProductUrl         = result.SpecPageUrl,
                 SdsUrl             = result.SdsUrl,
@@ -873,7 +875,7 @@ public class InventoryController : Controller
                         aiResult.CureTimeMinutes        ??= full.CureTimeMinutes;
                         aiResult.RequiresClearCoat      ??= full.RequiresClearCoat;
                         aiResult.CoverageSqFtPerLb      ??= full.CoverageSqFtPerLb;
-                        aiResult.TransferEfficiency     ??= full.TransferEfficiency;
+                        aiResult.TransferEfficiency     ??= GetEffectiveTransferEfficiency(full.TransferEfficiency);
                         aiResult.ManufacturerPartNumber ??= full.ManufacturerPartNumber;
                         aiResult.ColorName              ??= full.ColorName;
                         aiResult.ColorCode              ??= full.ColorCode;
@@ -952,7 +954,7 @@ public class InventoryController : Controller
             colorFamilies          = aiResult.ColorFamilies,
             requiresClearCoat      = aiResult.RequiresClearCoat,
             coverageSqFtPerLb      = aiResult.CoverageSqFtPerLb,
-            transferEfficiency     = aiResult.TransferEfficiency,
+            transferEfficiency     = aiResult.TransferEfficiency ?? DefaultTransferEfficiency,
             unitPrice              = aiResult.UnitCostPerLb ?? 0m,
             imageUrl               = aiResult.ImageUrl,
             productUrl             = aiResult.SpecPageUrl,
@@ -1104,13 +1106,18 @@ public class InventoryController : Controller
                 colorFamilies = p.ColorFamilies,
                 requiresClearCoat = p.RequiresClearCoat,
                 coverageSqFtPerLb = p.CoverageSqFtPerLb,
-                transferEfficiency = p.TransferEfficiency
+                transferEfficiency = GetEffectiveTransferEfficiency(p.TransferEfficiency)
             })
             .ToList();
 
         return Json(results);
     }
 
+    private static decimal GetEffectiveTransferEfficiency(decimal? transferEfficiency)
+    {
+        return transferEfficiency ?? DefaultTransferEfficiency;
+    }
+
     /// <summary>
     /// Normalizes a string to title-case using the current culture's TextInfo. Applied to
     /// inventory item names on create and edit so the list view is consistently formatted