feat(website): show the sponsor band on category pages

The sponsor band rendered only on the homepage, so visitors who entered on a category page and never opened the homepage saw no sponsors. Category, subcategory, group, and Stdlib pages now show the same band between the hero and the table.

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

DESIGN.md

@@ -162,7 +162,7 @@ The component vocabulary is small and table-led. Source of truth: `website/stati
 - **Hero**. Magazine-cover headline, dark earthy ground, kicker and proof microcopy, primary CTA button using `--hero-btn-start` / `--hero-btn-end`. Subtle grid plus slow sheen. Respects `prefers-reduced-motion`.
 - **Jump links**. One per use case in a category hero, plus one for the guide. Underlined like the intro's links, with a trailing ↓. Never tag-styled: tags filter the table or open another page, jump links only scroll.
 - **Guide band**. Everything in a category intro after its "How to choose" list. It sits below the table on the hero's dark gradient, with its H2 above the text.
-- **Sponsor band**. Sits below the hero on the home page, on `--bg-paper-strong`. Editorial layout, not a logo wall. Sponsor links share the global accent treatment.
+- **Sponsor band**. Sits below the hero on the home page and category pages, on `--bg-paper-strong`. Editorial layout, not a logo wall. Sponsor links share the global accent treatment.
 - **CTA**. Warm `--cta-bg`, full-bleed within shell. The button itself uses accent tokens.
 - **Footer**. Dark warm charcoal, part of the same system. Footer links share the global hover and focus treatment.
 - **Search**. Pill input with `--search-inset` interior and `--search-focus-ring` focus ring. Focus shadow uses `--search-focus-shadow`.

website/build.py

@@ -894,6 +894,7 @@ def build(repo_root: Path) -> None:
                 parent_category=parent_category,
                 group_categories=group_categories,
                 category_json_ld=category_json_ld,
+                sponsors=sponsors,
             ),
             encoding="utf-8",
         )

website/templates/category.html

@@ -208,6 +208,8 @@
           <td></td>
         </tr>
 {% endmacro %}
+{% include "_sponsor_band.html" %}
+
 <section class="results-section" id="library-index">
   <div class="results-intro section-shell" data-reveal>
     {% if entry_groups %}

website/tests/test_build.py

@@ -490,6 +490,37 @@ class TestBuild:
         assert 'href="https://sponsor.example.com/?ref=x&utm_source=awesome-python&utm_content=website"' in index_html
         assert "utm_content=readme" not in index_html
 
+    def test_category_page_shows_sponsor_band(self, tmp_path):
+        readme = textwrap.dedent("""\
+            # Awesome Python
+
+            Intro.
+
+            ## **Sponsors**
+
+            - [Sponsor](https://sponsor.example.com) - Sponsored tool.
+
+            ## Projects
+
+            **Tools**
+
+            ## Widgets
+
+            - [w1](https://example.com) - A widget.
+
+            # Contributing
+
+            Help!
+        """)
+        (tmp_path / "README.md").write_text(readme, encoding="utf-8")
+        self._copy_real_templates(tmp_path)
+
+        build(tmp_path)
+
+        category_html = (tmp_path / "website" / "output" / "categories" / "widgets" / "index.html").read_text(encoding="utf-8")
+        assert 'href="https://sponsor.example.com"' in category_html
+        assert '<span class="sponsor-name">Sponsor</span>' in category_html
+
     def test_build_cleans_stale_output(self, tmp_path):
         readme = textwrap.dedent("""\
             # T