Promote job powders to top of Log Material dropdown

Powders already assigned to this job's coats appear under a 'This Job'
section header, then a divider, then 'All Inventory' — so the most
relevant choices are always one click away.

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

src/PowderCoating.Web/Controllers/JobsController.cs

@@ -503,9 +503,17 @@ public class JobsController : Controller
                 .OrderBy(i => i.Name)
                 .Select(i => new { i.Id, i.Name, i.Manufacturer, i.UnitOfMeasure, i.QuantityOnHand })
                 .ToList();
-            ViewBag.InventoryItemsForModal = System.Text.Json.JsonSerializer.Serialize(
-                inventoryItemsForModal,
-                new System.Text.Json.JsonSerializerOptions { PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase });
+            var jsonOpts = new System.Text.Json.JsonSerializerOptions { PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase };
+            ViewBag.InventoryItemsForModal = System.Text.Json.JsonSerializer.Serialize(inventoryItemsForModal, jsonOpts);
+
+            // IDs of powders already assigned to this job's coats — shown at top of log-material dropdown
+            var jobPowderIds = (jobDto.Items ?? new List<PowderCoating.Application.DTOs.Job.JobItemDto>())
+                .SelectMany(i => i.Coats ?? new List<PowderCoating.Application.DTOs.Job.JobItemCoatDto>())
+                .Where(c => c.InventoryItemId.HasValue)
+                .Select(c => c.InventoryItemId!.Value)
+                .Distinct()
+                .ToList();
+            ViewBag.JobPowderIds = System.Text.Json.JsonSerializer.Serialize(jobPowderIds, jsonOpts);
 
             // Pre-logged powder grouped by InventoryItemId (for Complete Job modal pre-fill)
             ViewBag.PreLoggedPowder = allJobTransactions