Remove ShopWorker entity and migrate worker identity to ApplicationUser

Removes the ShopWorker and ShopWorkerRoleCost entities, all related DTOs,
mappings, controllers, views, and import/export paths. Worker identity is
now handled entirely through ApplicationUser with per-user LaborCostPerHour.
ShopWorkerRoleCosts table remains in production pending manual data migration.

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

src/PowderCoating.Application/Interfaces/ICsvImportService.cs

@@ -136,18 +136,7 @@ public interface ICsvImportService
     /// </summary>
     Task<CsvImportResultDto> ImportVendorsAsync(Stream csvStream, int companyId);
 
-    /// <summary>
-    /// Generate a CSV template file for shop worker imports.
-    /// </summary>
-    byte[] GenerateShopWorkerTemplate();
-
-    /// <summary>
-    /// Import shop workers from a CSV stream.
-    /// Updates existing workers matched by Name; creates new ones otherwise.
-    /// </summary>
-    Task<CsvImportResultDto> ImportShopWorkersAsync(Stream csvStream, int companyId);
-
-    /// <summary>
+/// <summary>
     /// Generate a CSV template file for prep service imports.
     /// </summary>
     byte[] GeneratePrepServiceTemplate();