增加了组内可见的公告，编辑了对应的 models 和 js

announcement/models.py

@@ -2,6 +2,7 @@
 from django.db import models
 
 from account.models import User
+from group.models import Group
 
 
 class Announcement(models.Model):
@@ -17,6 +18,9 @@ class Announcement(models.Model):
     last_update_time = models.DateTimeField(auto_now=True)
     # 是否可见 false的话相当于删除
     visible = models.BooleanField(default=True)
+    # 公告可见范围 0是全局可见 1是部分小组可见，需要在下面的字段中存储可见的小组
+    is_global = models.BooleanField()
+    groups = models.ManyToManyField(Group)
 
     class Meta:
         db_table = "announcement"