feat: 新增隐私政策内容页(apps.core.SimpleContentPage)及seed命令，更新设计文档

apps/core/tests.py

@@ -2,6 +2,7 @@
 import pytest
 
 from apps.core.blocks import FormBlock
+from apps.core.models import SimpleContentPage
 from apps.forms.models import FormDefinition, FormDefinitionField
 
 pytestmark = pytest.mark.django_db
@@ -60,3 +61,17 @@ def test_form_block_api_representation_handles_empty_form():
     block = FormBlock()
     result = block.get_api_representation({"form": None})
     assert result == {"form": None}
+
+
+def test_simple_content_page_can_be_created_under_home(home_page):
+    """隐私政策等法务页面应可作为 HomePage 的子页面创建，并保留富文本内容。"""
+    page = SimpleContentPage(
+        title="隐私政策",
+        slug="privacy-policy",
+        body="<p>我们重视您的个人信息保护。</p>",
+    )
+    home_page.add_child(instance=page)
+
+    page.refresh_from_db()
+    assert SimpleContentPage.objects.live().descendant_of(home_page).count() == 1
+    assert "个人信息保护" in page.body