fix(test): ensure vault-hier processes are terminated

- Add `killall vault-hier` to cleanup script in `test_local.sh`.
- Prevent potential leftover processes from interfering with tests.

test_local.sh

@@ -53,6 +53,7 @@ cleanup() {
         kill -9 $VAULT_PID 2>/dev/null || true
         rm -f "$VAULT_PID_FILE"
     fi
+    killall vault-hier
     rm -f test_document.txt
     rm -rf /tmp/vault-test
     # We'll keep the logs for inspection