chore: apply ruff auto-fixes and remove dead AST scripts

summarize.py

@@ -171,7 +171,7 @@ def summarise_items(file_items: list[dict]) -> list[dict]:
   content = item.get("content", "")
   error = item.get("error", False)
   if error or path is None:
-   summary = f"_Error reading file_"
+   summary = "_Error reading file_"
   else:
    p = Path(path) if not isinstance(path, Path) else path
    summary = summarise_file(p, content)