Replace stored-procedure repositories with Dapper-based repositories

Removes the USP_* stored procedures for Auth, Location, and Brewery
data access in favour of services built with Dapper.

Adds a new Features.Locations slice and optimistic concurrency support
for the Brewery slice.

web/backend/Features/Features.Breweries/Commands/UpdateBrewery/UpdateBreweryCommand.cs

@@ -14,10 +14,13 @@ public record UpdateBreweryLocation(
 
 /// <summary>
 ///     Updates an existing brewery post. Bound directly from the request body of <c>PUT /api/brewery/{id}</c>.
-///     A <c>null</c> <see cref="Location" /> clears the brewery's location.
+///     A <c>null</c> <see cref="Location" /> clears the brewery's location. <see cref="Timer" /> must be the
+///     row-version last read for this brewery (e.g. from a prior <c>GET</c>); the update is rejected with a
+///     <c>409 Conflict</c> if the brewery was modified since then.
 /// </summary>
 public record UpdateBreweryCommand(
     Guid BreweryPostId,
+    byte[] Timer,
     Guid PostedById,
     string BreweryName,
     string Description,

web/backend/Features/Features.Breweries/Commands/UpdateBrewery/UpdateBreweryHandler.cs

@@ -12,6 +12,14 @@ public class UpdateBreweryHandler(IBreweryRepository repository)
     ///     Updates an existing brewery post. If <paramref name="request" /> has no <c>Location</c>,
     ///     the brewery's location is cleared.
     /// </summary>
+    /// <exception cref="Domain.Exceptions.NotFoundException">
+    ///     Thrown when no brewery exists with <paramref name="request" />'s <c>BreweryPostId</c>, or its
+    ///     location's <c>CityId</c> does not exist.
+    /// </exception>
+    /// <exception cref="Domain.Exceptions.ConflictException">
+    ///     Thrown when the brewery was modified by another request since <paramref name="request" />.
+    ///     <c>Timer</c> was read.
+    /// </exception>
     public async Task<BreweryDto> Handle(
         UpdateBreweryCommand request,
         CancellationToken cancellationToken
@@ -23,6 +31,7 @@ public class UpdateBreweryHandler(IBreweryRepository repository)
             PostedById = request.PostedById,
             BreweryName = request.BreweryName,
             Description = request.Description,
+            Timer = request.Timer,
             UpdatedAt = DateTime.UtcNow,
             Location = request.Location is null
                 ? null
@@ -38,7 +47,7 @@ public class UpdateBreweryHandler(IBreweryRepository repository)
                 },
         };
 
-        await repository.UpdateAsync(entity);
-        return entity.ToDto();
+        BreweryPost updated = await repository.UpdateAsync(entity);
+        return updated.ToDto();
     }
 }

web/backend/Features/Features.Breweries/Commands/UpdateBrewery/UpdateBreweryValidator.cs

@@ -0,0 +1,13 @@
+using FluentValidation;
+
+namespace Features.Breweries.Commands.UpdateBrewery;
+
+public class UpdateBreweryValidator : AbstractValidator<UpdateBreweryCommand>
+{
+    public UpdateBreweryValidator()
+    {
+        RuleFor(x => x.Timer)
+            .NotEmpty()
+            .WithMessage("Timer is required to detect conflicting concurrent updates.");
+    }
+}