fix test: Use explicit shell for cat command

Author: tryweb

test/run-tests.sh

@@ -281,7 +281,7 @@ echo ""
 echo "--- Superpowers (Agentic Skills Framework) ---"
 
 echo "opencode.json content:"
-docker exec "$CONTAINER" cat ~/.config/opencode/opencode.json 2>/dev/null || echo "FILE_NOT_FOUND"
+docker exec "$CONTAINER" sh -c 'cat /home/devuser/.config/opencode/opencode.json' 2>/dev/null || echo "FILE_NOT_FOUND"
 echo "---"
 
 if docker exec "$CONTAINER" jq -r '.plugin | join(" ")' ~/.config/opencode/opencode.json 2>/dev/null | grep -q "superpowers"; then