style(sdk): strip whitespace when normalizing write_concern for causal-read check

Author: polaz

coordinode/coordinode/client.py

@@ -278,7 +278,7 @@ async def cypher(
         # Causal reads (after_index > 0) are only satisfiable when writes were
         # acknowledged by a majority; otherwise the referenced index may never
         # replicate and the read would hang. Mirror the server's rejection.
-        if after_index is not None and after_index > 0 and (write_concern or "").lower() != "majority":
+        if after_index is not None and after_index > 0 and (write_concern or "").strip().lower() != "majority":
             raise ValueError(
                 "after_index > 0 requires write_concern='majority' — causal reads "
                 "depend on majority-committed writes. Pass write_concern='majority'."