xint-data-dir-symlink-outside-releases

xint writes runtime data (api-costs.json, reliability-metrics.json, auth tokens) to an internal data/ directory within its versioned release folder (releases/<version>/data/). This data gets wiped on every version upgrade. Fix: create persistent /opt/infra/xint/data/ outside releases and symlink releases/<version>/data/opt/infra/xint/data/ immediately after installation. Any xint upgrade must re-create this symlink.