refactor(readme_parser): consolidate state reset to tail of flush_group

State reset (current_group_name = None, current_group_cats = []) was
duplicated in both branches of the early-return guard. Move it after
the conditional so it runs exactly once regardless of path.

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

website/readme_parser.py

@@ -324,10 +324,7 @@ def _parse_grouped_sections(
 
     def flush_group() -> None:
         nonlocal current_group_name, current_group_cats
-        if not current_group_cats:
-            current_group_name = None
-            current_group_cats = []
-            return
+        if current_group_cats:
             name = current_group_name or "Other"
             groups.append(ParsedGroup(
                 name=name,