⏱️ 数据库迁移：添加 expires_at 字段

backend/meetings/migrations/0003_meeting_expires_at.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.3 on 2026-04-05 01:44
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("meetings", "0002_meeting_host_agent_id_meeting_host_instance_id_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="meeting",
+            name="expires_at",
+            field=models.DateTimeField(blank=True, null=True, verbose_name="过期时间"),
+        ),
+    ]