feat(TfFile): Entität mit Metadaten und Schema-Zuordnung hinzufügen

- Enthält detaillierte Schema-Zuordnung mit Validierungshinweisen für nullfähige Felder.
- Ermöglicht die Verfolgung von Dateimetadaten innerhalb des Workflow-Systems.

src/WorkFlow.Domain/Entities/TfFile.cs

@@ -0,0 +1,60 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace WorkFlow.Domain.Entities;
+
+[Table("TBMWF_TF_FILES")]
+public class TfFile
+{
+    [Key]
+    [Column("GUID", TypeName = "bigint")]
+    public long Id { get; set; }
+
+    [Required]
+    [Column("OBJ_STATE_ID", TypeName = "bigint")]
+    public long ObjStateId { get; set; }
+
+    [Required]
+    [StringLength(512)]
+    [Column("F_FAPTH", TypeName = "nvarchar(512)")]
+    public string FFapth { get; set; } = null!;
+
+    /// <summary>
+    /// Although this field is marked as <c>nullable</c> in the database schema to allow 
+    /// for greater flexibility during database-level operations or migrations, it is 
+    /// treated as <c>required</c> and <c>not null</c> within the application logic. 
+    /// Validation should be enforced at the application level to ensure a value is provided.
+    /// </summary>
+    [Column("HEADLINE", TypeName = "nvarchar(100)")]
+    public string? Headline { get; set; }
+
+    [StringLength(100)]
+    [Column("SUBLINE", TypeName = "nvarchar(100)")]
+    public string? Subline { get; set; }
+
+    [StringLength(250)]
+    [Column("COMMENT", TypeName = "nvarchar(250)")]
+    public string? Comment { get; set; }
+
+    [StringLength(100)]
+    [Column("ICON", TypeName = "nvarchar(100)")]
+    public string? Icon { get; set; }
+
+    /// <summary>
+    /// Although this field is marked as <c>nullable</c> in the database schema to allow 
+    /// for greater flexibility during database-level operations or migrations, it is 
+    /// treated as <c>required</c> and <c>not null</c> within the application logic. 
+    /// Validation should be enforced at the application level to ensure a value is provided.
+    /// </summary>
+    [Column("ADDED_WHO", TypeName = "nvarchar(100)")]
+    public string? AddedWho { get; set; }
+
+    /// <summary>
+    /// Although this field is marked as <c>nullable</c> in the database schema to allow 
+    /// for greater flexibility during database-level operations or migrations, it is 
+    /// treated as <c>required</c> and <c>not null</c> within the application logic. 
+    /// Validation should be enforced at the application level to ensure a value is provided.
+    /// </summary>
+    [Column("ADDED_WHEN", TypeName = "datetime")]
+    public DateTime? AddedWhen { get; set; }
+}