Add in-memory DB support for .NET 4.8 and .NET 8 testing

Introduced a `DbConnection` constructor in `JobRunnerDbContext`
for Entity Framework 6 to enable in-memory testing with the
Effort library. Added conditional compilation to support both
.NET Framework 4.8 and .NET 8.

Implemented `AddInfrastructureInMemory` in `DependencyExtension`
to register services with in-memory databases:
- For .NET 4.8, uses Effort's transient connection.
- For .NET 8, uses EF Core's in-memory provider.

Registered AutoMapper in both methods for object mapping. Added
`EntityMappingProfile` to define AutoMapper configurations,
enforcing explicit DTO-to-entity mappings. These changes improve
testability and maintainability across .NET versions.

ECMJobRunner.Infrastructure/Mapping/EntityMappingProfile.cs

@@ -0,0 +1,22 @@
+using AutoMapper;
+using ECMJobRunner.Domain.Entities;
+
+namespace ECMJobRunner.Infrastructure.Mapping
+{
+    /// <summary>
+    /// AutoMapper profile for entity mappings
+    /// </summary>
+    public class EntityMappingProfile : Profile
+    {
+        /// <summary>
+        /// Constructor configuring AutoMapper mappings for all entities
+        /// </summary>
+        public EntityMappingProfile()
+        {
+            // Note: object -> Entity mappings are intentionally removed
+            // AutoMapper cannot map from object type due to reflection limitations
+            // Callers should use explicit DTO types and create specific mappings
+            // Example: CreateMap<YourDto, CfgProfile>() in your own AutoMapper profile
+        }
+    }
+}