新增每门课程的“优先上课日 / 偏好节次范围”，与硬性可排范围分离。

遗传算法在满足冲突、容量、场地等硬约束后，优先满足课程偏好；偏好无法满足时仍会安排可行课次。
管理员可通过“课程偏好权重”控制偏好的影响程度。
修复遗传适应度：教室容量冗余、同一任务分散、日负载和实验场地偏好现在都会实际参与种群评分

tests/Jiaowu.Api.Tests/ScheduleSettingsControllerTests.cs

@@ -219,6 +219,9 @@ public sealed class ScheduleSettingsControllerTests
             AllowedDayOfWeeks = "1,3,5",
             EarliestPeriod = 1,
             LatestPeriod = 8,
+            PreferredDayOfWeeks = "2,4",
+            PreferredEarliestPeriod = 3,
+            PreferredLatestPeriod = 6,
             AllowedClassrooms =
             [
                 new TeachingTaskAllowedClassroom { Classroom = classroom }
@@ -243,6 +246,7 @@ public sealed class ScheduleSettingsControllerTests
         Assert.Contains(classroom.Id.ToString(), json);
         Assert.Contains("\"WeeklyHours\":4", json);
         Assert.Contains("\"CoursePracticeHours\":16", json);
+        Assert.Contains("\"PreferredDayOfWeeks\":[2,4]", json);
     }
 
     [Fact]