Migrate Breweries to a vertical slice (Features.Breweries)

Moves brewery CRUD from the Service.Breweries/Infrastructure.Repository
layered split into a single Features.Breweries project: MediatR
commands/queries replace BreweryService, and the repository moves in
alongside its own controller. Extracts Infrastructure.Sql out of
Infrastructure.Repository (just the generic ADO.NET connection/base-repo
plumbing) since Breweries no longer needs the rest of that project, while
Auth and UserAccount repos still do until their own migration.

Also fixes the API.Core and Infrastructure.Repository.Tests Dockerfiles,
which were restoring against COPY destinations that didn't match the
projects' actual relative paths (silently working only because of the
COPY . . that followed); both now restore against Core.slnx with correctly
nested paths, verified with a real docker build.

web/backend/Infrastructure/Infrastructure.Sql/Repository.cs

@@ -0,0 +1,32 @@
+using System.Data.Common;
+
+namespace Infrastructure.Sql;
+
+/// <summary>
+/// Base class for ADO.NET-based repositories, providing shared connection creation and
+/// entity-mapping infrastructure for derived repository implementations.
+/// </summary>
+/// <typeparam name="T">The entity type managed by the repository.</typeparam>
+/// <param name="connectionFactory">The factory used to create database connections.</param>
+public abstract class Repository<T>(ISqlConnectionFactory connectionFactory)
+    where T : class
+{
+    /// <summary>
+    /// Creates and opens a new database connection using the configured <see cref="ISqlConnectionFactory"/>.
+    /// </summary>
+    /// <returns>An open <see cref="DbConnection"/> ready for use.</returns>
+    /// <exception cref="DbException">Thrown when the connection cannot be opened.</exception>
+    protected async Task<DbConnection> CreateConnection()
+    {
+        var connection = connectionFactory.CreateConnection();
+        await connection.OpenAsync();
+        return connection;
+    }
+
+    /// <summary>
+    /// Maps the current row of a data reader to an instance of <typeparamref name="T"/>.
+    /// </summary>
+    /// <param name="reader">The data reader positioned on the row to map.</param>
+    /// <returns>The mapped entity instance.</returns>
+    protected abstract T MapToEntity(DbDataReader reader);
+}