Add ECMJobRunner.Domain entities and documentation

Introduced the `ECMJobRunner.Domain` project to support both
.NET Framework 4.8 and .NET 8.0. Added `Profile`,
`ProfileSqlJob`, and `ProfileHistory` entities to map to the
database schema, including relationships and audit fields.

Updated `ECMJobRunner.Domain.csproj` to enable multi-targeting
and added dependencies for Entity Framework 6.5.1 and EF Core
8.0.11. Enabled nullable reference types and set the language
version to `latest`.

Added comprehensive documentation in `AGENTS.md` detailing the
project structure, entities, database schema, and build
instructions.

ECMJobRunner.Domain/Entities/Profile.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace ECMJobRunner.Domain.Entities
+{
+    /// <summary>
+    /// Job Runner Configuration Profile Entity
+    /// Represents a job runner profile configuration
+    /// Type: 0 = ADSync; 1 = GraphQL; 2 = SQL-Job; 3 = SQL and REST-Job
+    /// </summary>
+    [Table("TBJR_CFG_PROFILE", Schema = "dbo")]
+    public class Profile
+    {
+        /// <summary>
+        /// Primary Key
+        /// </summary>
+        [Key]
+        [Column("PK_TBJR_CFG_PROFILE_ID")]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        public long Id { get; set; }
+
+        /// <summary>
+        /// Active / Inactive switch
+        /// </summary>
+        [Required]
+        [Column("ACTIVE")]
+        public bool Active { get; set; } = true;
+
+        /// <summary>
+        /// Optional profile name
+        /// </summary>
+        [Required]
+        [Column("PROFILE_NAME")]
+        [MaxLength(150)]
+        public string ProfileName { get; set; } = null!;
+
+        /// <summary>
+        /// Profile type: 0 = ADSync; 1 = GraphQL; 2 = SQL-Job; 3 = SQL and REST-Job
+        /// </summary>
+        [Required]
+        [Column("TYPE_ID")]
+        public byte TypeId { get; set; }
+
+        /// <summary>
+        /// Schedule in Cron format
+        /// </summary>
+        [Required]
+        [Column("SCHEDULE")]
+        [MaxLength(150)]
+        public string Schedule { get; set; } = "0 30 4 ? * MON-SAT";
+
+        /// <summary>
+        /// Optional description
+        /// </summary>
+        [Column("COMMENT")]
+        [MaxLength(500)]
+        public string? Comment { get; set; }
+
+        /// <summary>
+        /// Created by
+        /// </summary>
+        [Required]
+        [Column("ADDED_WHO")]
+        [MaxLength(50)]
+        public string AddedWho { get; set; } = "DEFAULT";
+
+        /// <summary>
+        /// Created at
+        /// </summary>
+        [Required]
+        [Column("ADDED_WHEN")]
+        public DateTime AddedWhen { get; set; } = DateTime.Now;
+
+        /// <summary>
+        /// Modified by
+        /// </summary>
+        [Column("CHANGED_WHO")]
+        [MaxLength(50)]
+        public string? ChangedWho { get; set; }
+
+        /// <summary>
+        /// Modified at
+        /// </summary>
+        [Column("CHANGED_WHEN")]
+        public DateTime? ChangedWhen { get; set; }
+
+        // Navigation properties
+        
+        /// <summary>
+        /// SQL Jobs associated with this profile
+        /// </summary>
+        public virtual ICollection<ProfileSqlJob> SqlJobs { get; set; } = new List<ProfileSqlJob>();
+
+        /// <summary>
+        /// Profile execution history
+        /// </summary>
+        public virtual ICollection<ProfileHistory> ProfileHistories { get; set; } = new List<ProfileHistory>();
+    }
+}