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.Domain/ValueObjects/LifeCycleStatus.cs

@@ -0,0 +1,8 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum LifeCycleStatus
+    {
+        Active = 0,
+        Removing = 1
+    }
+}

Musify.Domain/ValueObjects/ProcessingStatus.cs

@@ -0,0 +1,10 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum ProcessingStatus
+    {
+        Pending = 0,
+        Processing = 1,
+        Completed = 2,
+        Failed = 3
+    }
+}

Musify.Domain/ValueObjects/UploadIntentPurpose.cs

@@ -0,0 +1,9 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum UploadIntentPurpose
+    {
+        PlayListPicture,
+        TrackPicture,
+        TrackAudio,
+    }
+}

Musify.Domain/ValueObjects/UploadIntentStatus.cs

@@ -0,0 +1,9 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum UploadIntentStatus
+    {
+        Issued,
+        Consumed,
+        Expired,
+    }
+}

Musify.Domain/ValueObjects/UploadState.cs

@@ -0,0 +1,9 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum UploadState
+    {
+        Pending,
+        Failed,
+        Successful,
+    }
+}