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

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Musify.Domain/Entities/PlayList.cs

@@ -0,0 +1,61 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.Abstractions;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("PlayLists")]
+    public class PlayList : IAuditable
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string Name { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string NormalizedName { get; set; }
+
+        [Required]
+        [MaxLength(256)]
+        public required string Description { get; set; } = "No description was provided.";
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string SmallPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string MediumPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string LargePictureName { get; set; }
+
+        [Required]
+        public LifeCycleStatus LifeCycleStatus { get; set; } = LifeCycleStatus.Active;
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; }
+
+        public ICollection<PlayListHasTrack> PlayListTracks { get; set; } = new List<PlayListHasTrack>();
+    }
+}

Musify.Domain/Entities/PlayListHasTrack.cs

@@ -0,0 +1,30 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("PlayListHasTrack")]
+    public class PlayListHasTrack
+    {
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required Guid PlayListId { get; set; }
+
+        [Required]
+        public required Guid TrackId { get; set; }
+
+        [Required]
+        public int Position { get; set; } = 0;
+
+        [Required]
+        public DateTime AddedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(PlayListId)) ]
+        public PlayList PlayList { get; set; }
+
+        [ForeignKey(nameof(TrackId)) ]
+        public Track Track { get; set; }
+    }
+}

Musify.Domain/Entities/Track.cs

@@ -0,0 +1,78 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Diagnostics.CodeAnalysis;
+
+using Musify.Domain.Abstractions;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    public class Track : IAuditable
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        [MaxLength(50)]
+        public required string Title { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string NormalizedTitle { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? SmallPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? MediumPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? LargePictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalAudioName { get; set; }
+
+        [MaxLength(64)]
+        public string? AudioFolderName { get; set; }
+
+        [Required]
+        public ProcessingStatus PicturesProcessingStatus { get; set; } = ProcessingStatus.Pending;
+
+        [Required]
+        public ProcessingStatus AudioTranscodeProcessingStatus { get; set; } = ProcessingStatus.Pending;
+
+        [Required]
+        public LifeCycleStatus LifeCycleStatus { get; set; } = LifeCycleStatus.Active;
+
+        [Required]
+        public int RetryCount { get; set; } = 0;
+
+        public DateTime? LastRetryAt { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        public ICollection<UserHasTrack> UserTracks { get; set; } = new List<UserHasTrack>();
+
+        public ICollection<PlayListHasTrack> PlayListTracks { get; set; } = new List<PlayListHasTrack>();
+
+        [NotMapped]
+        [MemberNotNullWhen(true, nameof(SmallPictureName)) ]
+        [MemberNotNullWhen(true, nameof(MediumPictureName)) ]
+        [MemberNotNullWhen(true, nameof(LargePictureName)) ]
+        public bool IsPicturesProcessed => PicturesProcessingStatus == ProcessingStatus.Completed;
+
+        [NotMapped]
+        [MemberNotNullWhen(true, nameof(AudioFolderName)) ]
+        public bool IsAudioProcessed => AudioTranscodeProcessingStatus == ProcessingStatus.Completed;
+    }
+}

Musify.Domain/Entities/Upload.cs

@@ -0,0 +1,29 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+    [Table("Upload")]
+    public class Upload
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required string Bucket { get; set; }
+
+        [Required]
+        public required string Key { get; set; }
+
+        [Required]
+        public required string ContentType { get; set; }
+
+        [Required]
+        public DateTime CreatedTime { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public UploadState State { get; set; } = UploadState.Pending;
+    }
+}

Musify.Domain/Entities/UploadIntent.cs

@@ -0,0 +1,46 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+    [Table("UploadIntents")]
+    public class UploadIntent
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string Bucket { get; set; }
+
+        [Required, MaxLength(512)]
+        public required string Key { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string ObjectName { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string ContentType { get; set; }
+
+        public long? ExpectedSizeBytes { get; set; }
+
+        [Required]
+        public UploadIntentPurpose Purpose { get; set; }
+
+        [Required]
+        public UploadIntentStatus Status { get; set; } = UploadIntentStatus.Issued;
+
+        [Required]
+        public DateTime ExpiresAt { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; } = null!;
+    }
+}

Musify.Domain/Entities/User.cs

@@ -0,0 +1,41 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using Musify.Domain.Abstractions;
+
+namespace Musify.Domain.Entities
+{
+    [Table("User")]
+    public class User : IAuditable
+    {
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public required long Id { get; set; }
+
+        [Required]
+        [MaxLength(48)]
+        public required string Name { get; set; }
+
+        [Required]
+        [MaxLength(48)]
+        public required string NormalizedName { get; set; }
+
+        [MaxLength(48)]
+        public string? FirstName { get; set; }
+
+        [MaxLength(48)]
+        public string? SecondName { get; set; }
+
+        [MaxLength(2048)]
+        public string? ProfilePictureUrl { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        public ICollection<UserHasTrack> UserTracks { get; set; } = new List<UserHasTrack>();
+
+        public ICollection<PlayList> PlayLists { get; set; } = new List<PlayList>();
+    }
+}

Musify.Domain/Entities/UserHasTrack.cs

@@ -0,0 +1,24 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("UserHasTrack")]
+    public class UserHasTrack
+    {
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required]
+        public required Guid TrackId { get; set; }
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; }
+
+        [ForeignKey(nameof(TrackId)) ]
+        public Track Track { get; set; }
+    }
+}