Implement requested workflow and UI updates

tests/Jiaowu.Api.Tests/ApprovalsControllerTests.cs

@@ -156,7 +156,14 @@ public sealed class ApprovalsControllerTests
                 }
             ]
         };
-        fixture.Db.AddRange(historicalTerm, historicalTask, sheet);
+        fixture.Db.AddRange(historicalTerm, historicalTask, sheet,
+            new CourseEquivalencyRule
+            {
+                OriginalCourseId = fixture.CurrentCourse.Id,
+                SubstituteCourseId = fixture.SubstituteCourse.Id,
+                IsEnabled = true,
+                Notes = "测试等价规则"
+            });
         await fixture.Db.SaveChangesAsync();
 
         var result = await fixture.Controller.ApplySubstitution(