Add Infrastructure layer with EF6/EF Core support

Introduced a robust Infrastructure layer for the ECMJobRunner system:
- Added `AGENTS.md` with detailed project documentation.
- Implemented generic repository and unit-of-work patterns.
- Added `CfgProfileRepository`, `ProfileSqlJobRepository`, and `ProfileHistoryRepository`.
- Integrated AutoMapper for DTO-to-entity mapping.
- Added multi-framework support for .NET Framework 4.8 (EF6) and .NET 8.0 (EF Core) using conditional compilation.
- Updated `ECMJobRunner.Infrastructure.csproj` with metadata fixes and dependencies.
- Introduced dependency injection extension for .NET 8.0.
- Enhanced project structure and database context with entity mappings.

ECMJobRunner.Infrastructure/DependencyExtension.cs

@@ -0,0 +1,41 @@
+#if NET48
+using System.Data.Entity;
+#else
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+#endif
+using ECMJobRunner.Domain.Interfaces;
+using ECMJobRunner.Infrastructure.Data;
+using ECMJobRunner.Infrastructure.Repositories;
+
+namespace ECMJobRunner.Infrastructure
+{
+#if !NET48
+    /// <summary>
+    /// Dependency injection extension methods for Infrastructure layer
+    /// </summary>
+    public static class DependencyExtension
+    {
+        /// <summary>
+        /// Add Infrastructure services to dependency injection container
+        /// </summary>
+        /// <param name="services">Service collection</param>
+        /// <param name="connectionString">Database connection string</param>
+        /// <returns>Service collection for chaining</returns>
+        public static IServiceCollection AddInfrastructure(this IServiceCollection services, string connectionString)
+        {
+            // Register DbContext
+            services.AddDbContext<JobRunnerDbContext>(options =>
+                options.UseSqlServer(connectionString));
+
+            // Register repositories
+            services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
+            services.AddScoped<ICfgProfileRepository, CfgProfileRepository>();
+            services.AddScoped<IProfileSqlJobRepository, ProfileSqlJobRepository>();
+            services.AddScoped<IProfileHistoryRepository, ProfileHistoryRepository>();
+
+            return services;
+        }
+    }
+#endif
+}