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/Features/Features.Breweries/Commands/CreateBrewery/CreateBreweryValidator.cs

@@ -0,0 +1,59 @@
+using FluentValidation;
+
+namespace Features.Breweries.Commands.CreateBrewery;
+
+/// <summary>
+/// Validates <see cref="CreateBreweryCommand"/> instances before they are processed.
+/// </summary>
+public class CreateBreweryValidator : AbstractValidator<CreateBreweryCommand>
+{
+    /// <summary>
+    /// Configures validation rules requiring <see cref="CreateBreweryCommand.PostedById"/>,
+    /// <see cref="CreateBreweryCommand.BreweryName"/>, <see cref="CreateBreweryCommand.Description"/>, and
+    /// <see cref="CreateBreweryCommand.Location"/> to be present, with length limits on the name, description,
+    /// address line 1, and postal code fields.
+    /// </summary>
+    public CreateBreweryValidator()
+    {
+        RuleFor(x => x.PostedById)
+            .NotEmpty()
+            .WithMessage("PostedById is required.");
+
+        RuleFor(x => x.BreweryName)
+            .NotEmpty()
+            .WithMessage("Brewery name is required.")
+            .MaximumLength(256)
+            .WithMessage("Brewery name cannot exceed 256 characters.");
+
+        RuleFor(x => x.Description)
+            .NotEmpty()
+            .WithMessage("Description is required.")
+            .MaximumLength(512)
+            .WithMessage("Description cannot exceed 512 characters.");
+
+        RuleFor(x => x.Location)
+            .NotNull()
+            .WithMessage("Location is required.");
+
+        RuleFor(x => x.Location.CityId)
+            .NotEmpty()
+            .When(x => x.Location is not null)
+            .WithMessage("CityId is required.");
+
+        RuleFor(x => x.Location.AddressLine1)
+            .NotEmpty()
+            .When(x => x.Location is not null)
+            .WithMessage("Address line 1 is required.")
+            .MaximumLength(256)
+            .When(x => x.Location is not null)
+            .WithMessage("Address line 1 cannot exceed 256 characters.");
+
+        RuleFor(x => x.Location.PostalCode)
+            .NotEmpty()
+            .When(x => x.Location is not null)
+            .WithMessage("Postal code is required.")
+            .MaximumLength(20)
+            .When(x => x.Location is not null)
+            .WithMessage("Postal code cannot exceed 20 characters.");
+    }
+}