Refactor DbContext and add IRecDbContext interface

Refactored `DependencyInjection` to use a generic `TRecDbContext`
for flexibility and added scoped registration for `IRecDbContext`.
Updated `RecDbContext` to implement the new `IRecDbContext`
interface, ensuring adherence to the application-layer contract.

Introduced the `IRecDbContext` interface in the application layer,
defining `DbSet` properties for key entities and a `SaveChangesAsync`
method. Updated `ReC.Infrastructure.csproj` to reference the
application project for interface access.

src/ReC.Infrastructure/RecDbContext.cs

@@ -1,9 +1,10 @@
 using Microsoft.EntityFrameworkCore;
+using ReC.Application.Common.Interfaces;
 using ReC.Domain.Entities;
 
 namespace ReC.Infrastructure;
 
-public class RecDbContext(DbContextOptions<RecDbContext> options) : DbContext(options)
+public class RecDbContext(DbContextOptions<RecDbContext> options) : DbContext(options), IRecDbContext
 {
     public DbSet<EndpointParam> EndpointParams { get; set; }