feat(website): show parent category breadcrumb on subcategory pages

Co-Authored-By: Claude <noreply@anthropic.com>

website/templates/category.html

@@ -24,6 +24,11 @@
     </nav>
 
     <div class="category-hero-copy">
+      {% if page_kind == "subcategory" and parent_category %}
+      <p class="category-breadcrumb">
+        <a href="/categories/{{ parent_category.slug }}/">{{ parent_category.name }}</a>
+      </p>
+      {% endif %}
       <h1>{{ category.name }}</h1>
       {% if category.description_html %}
       <p class="category-subtitle">{{ category.description_html | safe }}</p>

website/tests/test_build.py

@@ -577,6 +577,34 @@ class TestBuild:
         assert "fastapi" in async_
         assert "django" not in async_
 
+    def test_subcategory_page_shows_breadcrumb(self, tmp_path):
+        readme = textwrap.dedent("""\
+            # T
+
+            ---
+
+            **Web**
+
+            ## Web Frameworks
+
+            - Synchronous
+
+                - [django](https://example.com/django) - Sync.
+
+            # Contributing
+
+            Done.
+        """)
+        self._copy_real_templates(tmp_path)
+        (tmp_path / "README.md").write_text(readme, encoding="utf-8")
+        build(tmp_path)
+
+        site = tmp_path / "website" / "output"
+        sync = (site / "categories" / "web-frameworks" / "synchronous" / "index.html").read_text(encoding="utf-8")
+        assert 'href="/categories/web-frameworks/"' in sync
+        assert "Web Frameworks" in sync
+        assert "<h1>Synchronous</h1>" in sync
+
     def test_build_creates_group_pages(self, tmp_path):
         readme = textwrap.dedent("""\
             # T