feat(training): add TrainingAngleResult entity and DbSet

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Training/Data/TrainingAngleResult.cs

@@ -0,0 +1,20 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace OpenNest.Training.Data
+{
+    [Table("AngleResults")]
+    public class TrainingAngleResult
+    {
+        [Key]
+        public long Id { get; set; }
+
+        public long RunId { get; set; }
+        public double AngleDeg { get; set; }
+        public string Direction { get; set; }
+        public int PartCount { get; set; }
+
+        [ForeignKey(nameof(RunId))]
+        public TrainingRun Run { get; set; }
+    }
+}