fix: keep superpowers tree out of public docs build

Author: wesm

docs/zensical-docs.sh

@@ -70,6 +70,7 @@ tmp_config_base=""
     --exclude './.zensical-build.*' \
     --exclude './.ruff_cache' \
     --exclude './.mypy_cache' \
+    --exclude './superpowers' \
     --exclude './internal' \
     --exclude './overrides' \
     --exclude './scripts' \