fix(superset): align bootstrap with clickhousedb uri

- Why:
  - Superset bootstrap used outdated ClickHouse URI format and did not fail fast on init errors.
  - docs and exported dashboard metadata diverged from runtime connection settings.
- What:
  - build ClickHouse URI from env vars and use clickhousedb:// in init script.
  - refresh dataset metadata on existing datasets and surface import errors.
  - run create_dashboard during superset-init startup and align docs/exported URI references.
  - ignore node_modules in git.
- Check:
  - python3 -m py_compile superset/init_superset.py
  - manual dashboard smoke check in UI (charts render)

superset/dashboards/ecommerce_analytics.zip.json

@@ -188,7 +188,7 @@
     {
       "__Database__": {
         "database_name": "clickhouse_dwh",
-        "sqlalchemy_uri": "clickhouse+native://default@clickhouse:9000/default",
+        "sqlalchemy_uri": "clickhousedb://default:123456@clickhouse:8123/default",
         "expose_in_sqllab": true,
         "allow_ctas": false,
         "allow_cvas": false,