refactor: consolidate project structure by migrating authentication, identity, and shared UI components while removing legacy Web Client files.

src/NexusReader.Domain/Entities/Ebook.cs

@@ -0,0 +1,36 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace NexusReader.Domain.Entities;
+
+/// <summary>
+/// Represents an E-book uploaded or owned by a user.
+/// </summary>
+public class Ebook
+{
+    [Key]
+    public Guid Id { get; set; } = Guid.NewGuid();
+
+    [Required]
+    [MaxLength(255)]
+    public string Title { get; set; } = string.Empty;
+
+    [MaxLength(255)]
+    public string Author { get; set; } = "Unknown";
+
+    [Required]
+    public string FilePath { get; set; } = string.Empty;
+
+    public string? CoverUrl { get; set; }
+
+    public DateTime AddedDate { get; set; } = DateTime.UtcNow;
+
+    public DateTime? LastReadDate { get; set; }
+
+    // Relationship to NexusUser
+    [Required]
+    public string UserId { get; set; } = string.Empty;
+
+    [ForeignKey(nameof(UserId))]
+    public NexusUser? User { get; set; }
+}