📋 飞行侠添加：会议纪要生成

新增:
- meetings/utils.py: 纪要生成工具函数
  - generate_meeting_minutes(): 生成纪要数据
  - export_minutes_to_markdown(): 导出 Markdown
- meetings/views.py: minutes action
  - 支持 JSON 和 Markdown 两种格式
  - 自动统计参会者消息数
  - 提取待办事项
- test_minutes.py: 纪要测试脚本

使用:
- GET /api/v1/meetings/{id}/minutes/ → JSON
- GET /api/v1/meetings/{id}/minutes/?output=markdown → Markdown

backend/meeting_room/urls.py

@@ -1,5 +1,5 @@
 from django.contrib import admin
-from django.urls import path, include
+from django.urls import path, include, re_path
 from django.views.generic import TemplateView
 from rest_framework.routers import DefaultRouter
 from meetings.views import MeetingViewSet, ParticipantViewSet
@@ -12,7 +12,8 @@ router.register(r'meetings/(?P<meeting_pk>[^/.]+)/participants', ParticipantView
 urlpatterns = [
     path("admin/", admin.site.urls),
     path("", TemplateView.as_view(template_name="meeting_room.html"), name="home"),
-    path("api/v1/", include(router.urls)),
     path("api/v1/auth/login/", LoginView.as_view()),
     path("api/v1/auth/register/", RegisterView.as_view()),
+    re_path(r'^api/v1/meetings/(?P<pk>[^/.]+)/generate-minutes/$', MeetingViewSet.as_view({'get': 'minutes'}), name='meeting-minutes'),
+    path("api/v1/", include(router.urls)),
 ]