refactor: standardize project names to Musify.* and flatten layout

- Flatten nested per-repo folders into flat Musify.* projects at root
- Rename assemblies/csproj: Domain->Musify.Domain, Application->Musify.Application,
  Infrastructure->Musify.Infrastructure, WebApi->Musify.Api, Worker->Musify.Worker,
  StreamingGateway->Musify.StreamingGateway
- Rename WebApi.* namespaces to Musify.Api.*
- Update all ProjectReference paths and the solution file
- Consolidate stray per-repo dotfiles; add root .gitattributes
- Move flutter client out to _archive

Musify.Infrastructure/MassTransit/Activities/UploadIntents/ConsumeUploadIntentsActivity.cs

@@ -0,0 +1,62 @@
+using MassTransit;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Domain.ValueObjects;
+using Musify.Infrastructure.MassTransit.Arguments;
+using Musify.Infrastructure.MassTransit.Logs;
+
+namespace Musify.Infrastructure.MassTransit.Activities.UploadIntents
+{
+    internal class ConsumeUploadIntentsActivity(
+        IDatabase database,
+        ILogger<ConsumeUploadIntentsActivity> logger)
+        : IActivity<ConsumeUploadIntentsArguments, ConsumeUploadIntentsLog>
+    {
+        public const string ExecuteEndpointName = "consume-upload-intents";
+
+        public async Task<ExecutionResult> Execute(ExecuteContext<ConsumeUploadIntentsArguments> executeContext)
+        {
+            var intentIds = executeContext.Arguments.IntentIds;
+
+            var intents = await database.UploadIntents
+                .Where(i => intentIds.Contains(i.Id))
+                .ToListAsync(executeContext.CancellationToken);
+
+            foreach (var intent in intents)
+                intent.Status = UploadIntentStatus.Consumed;
+
+            await database.SaveChangesAsync(executeContext.CancellationToken);
+
+            logger.LogInformation("Marked {Count} upload intent(s) as consumed", intents.Count);
+
+            return executeContext.Completed(new ConsumeUploadIntentsLog(intentIds));
+        }
+
+        public async Task<CompensationResult> Compensate(CompensateContext<ConsumeUploadIntentsLog> compensateContext)
+        {
+            try
+            {
+                var intentIds = compensateContext.Log.IntentIds;
+
+                var intents = await database.UploadIntents
+                    .Where(i => intentIds.Contains(i.Id))
+                    .ToListAsync(compensateContext.CancellationToken);
+
+                foreach (var intent in intents)
+                    intent.Status = UploadIntentStatus.Issued;
+
+                await database.SaveChangesAsync(compensateContext.CancellationToken);
+
+                logger.LogInformation("Reverted {Count} upload intent(s) back to Issued", intents.Count);
+
+                return compensateContext.Compensated();
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to compensate upload intent consumption");
+                return compensateContext.Failed(exception);
+            }
+        }
+    }
+}