feat(admin): 添加FamilyMember模型的后台管理配置

在Django admin后台中注册FamilyMember模型，并配置列表显示字段和搜索字段

core/admin.py

@@ -5,6 +5,7 @@ from .models import (
     Priority,
     Status,
     PlanType,
+    FamilyMember,
     ReadingRecord,
     InsightRecord,
     FamilyTask,
@@ -13,6 +14,12 @@ from .models import (
 )
 
 
+@admin.register(FamilyMember)
+class FamilyMemberAdmin(admin.ModelAdmin):
+    list_display = ('name', 'created_at', 'updated_at')
+    search_fields = ('name',)
+
+
 @admin.register(ReadingType)
 class ReadingTypeAdmin(admin.ModelAdmin):
     list_display = ('name', 'created_at', 'updated_at')