Fix EF Core timestamp population by using mutable properties and ValueGenerated configuration

src/csharp/LampControlApi/Infrastructure/Database/LampControlDbContext.cs

@@ -49,11 +49,13 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
                 entity.Property(e => e.CreatedAt)
                     .HasColumnName("created_at")
-                    .IsRequired();
+                    .IsRequired()
+                    .ValueGeneratedOnAdd();
 
                 entity.Property(e => e.UpdatedAt)
                     .HasColumnName("updated_at")
-                    .IsRequired();
+                    .IsRequired()
+                    .ValueGeneratedOnAddOrUpdate();
 
                 entity.Property(e => e.DeletedAt)
                     .HasColumnName("deleted_at");

src/csharp/LampControlApi/Infrastructure/Database/LampDbEntity.cs

@@ -4,33 +4,35 @@ namespace LampControlApi.Infrastructure.Database
 {
     /// <summary>
     /// Database entity for the lamp table.
-    /// Uses init setters for EF Core compatibility while maintaining immutability after construction.
+    /// Uses set accessors for EF Core compatibility to allow database-generated values.
     /// </summary>
     public sealed record LampDbEntity
     {
         /// <summary>
-        /// Gets or initializes the unique identifier for the lamp.
+        /// Gets or sets the unique identifier for the lamp.
         /// </summary>
-        public Guid Id { get; init; }
+        public Guid Id { get; set; }
 
         /// <summary>
-        /// Gets a value indicating whether gets or initializes a value indicating whether the lamp is turned on (true) or off (false).
+        /// Gets or sets a value indicating whether the lamp is turned on (true) or off (false).
         /// </summary>
-        public bool IsOn { get; init; }
+        public bool IsOn { get; set; }
 
         /// <summary>
-        /// Gets or initializes the timestamp when the lamp was created.
+        /// Gets or sets the timestamp when the lamp was created.
+        /// Database-generated on insert.
         /// </summary>
-        public DateTimeOffset CreatedAt { get; init; }
+        public DateTimeOffset CreatedAt { get; set; }
 
         /// <summary>
-        /// Gets or initializes the timestamp when the lamp was last updated.
+        /// Gets or sets the timestamp when the lamp was last updated.
+        /// Database-generated on insert and update via trigger.
         /// </summary>
-        public DateTimeOffset UpdatedAt { get; init; }
+        public DateTimeOffset UpdatedAt { get; set; }
 
         /// <summary>
-        /// Gets or initializes the timestamp when the lamp was soft deleted, or null if active.
+        /// Gets or sets the timestamp when the lamp was soft deleted, or null if active.
         /// </summary>
-        public DateTimeOffset? DeletedAt { get; init; }
+        public DateTimeOffset? DeletedAt { get; set; }
     }
 }