Integrate EF Core with SQL Server and Infrastructure

Added `Microsoft.EntityFrameworkCore` and `ReC.Infrastructure` namespaces to `Program.cs` to enable EF Core functionality and infrastructure services. Configured the database context with a connection string from the app's configuration and added error handling for missing connection strings.

Updated `ReC.API.csproj` to include the `Microsoft.EntityFrameworkCore.SqlServer` NuGet package (v9.0.11) for SQL Server support. Added a project reference to `ReC.Infrastructure` to enable the API project to use the infrastructure layer.

src/ReC.API/Program.cs

@@ -1,6 +1,18 @@
+using Microsoft.EntityFrameworkCore;
+using ReC.Infrastructure;
+
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
+builder.Services.AddInfrastructureServices(options =>
+{
+    options.ConfigureDbContext((dbContextOpt) =>
+    {
+        var connectionString = builder.Configuration.GetConnectionString("Default") 
+                               ?? throw new InvalidOperationException("Connection string is not found.");
+        dbContextOpt.UseSqlServer(connectionString);
+    });
+});
 
 builder.Services.AddControllers();
 // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle