Exclude aep_list page from starlight-sidebar-topics

The starlight-sidebar-topics plugin requires all pages to either be in a
topic or explicitly excluded. Added /aep_list to the exclude list since
it's a special listing page that doesn't need topic-based routing.

The edition-specific aep_list pages (e.g., /aep-2026/aep_list) are already
excluded via the wildcard patterns for non-default editions.

Error: 'Failed to find the topic for the aep_list page.'

Author: claude

astro.config.mjs

@@ -43,6 +43,7 @@ export default defineConfig({
           exclude: [
             "/blog",
             "/blog/**/*",
+            "/aep_list",
             ...aepEditions.editions
               .filter((edition) => edition.folder !== ".")
               .flatMap((edition) => [