Implement comprehensive academic statistics and grade analysis workflows

src/Jiaowu.Api/Controllers/CourseAdjustmentsController.cs

@@ -142,7 +142,7 @@ public sealed class CourseAdjustmentsController(
             .ToList();
 
         var classrooms = await db.Classrooms.AsNoTracking()
-            .Where(x => x.IsEnabled)
+            .Where(x => x.IsEnabled && x.AvailabilityStatus == ClassroomAvailabilityStatus.Normal)
             .OrderBy(x => x.Building!.Campus!.SortOrder)
             .ThenBy(x => x.Building!.SortOrder)
             .ThenBy(x => x.SortOrder)
@@ -614,9 +614,10 @@ public sealed class CourseAdjustmentsController(
 
         if (request.ClassroomId.HasValue &&
             !await db.Classrooms.AsNoTracking().AnyAsync(x =>
-                x.Id == request.ClassroomId && x.IsEnabled,
+                x.Id == request.ClassroomId && x.IsEnabled &&
+                x.AvailabilityStatus == ClassroomAvailabilityStatus.Normal,
                 cancellationToken))
-            return ValidationProblem("目标教室不存在或已停用。");
+            return ValidationProblem("目标教室不存在、已停用或正在维修。");
 
         return null;
     }