Summary

• Add chdb/datastore.py shim so from chdb import datastore as pd works after chdb / chdb-core split
• Dynamically patch chdb.__version__ to the chdb pip-package version (instead of chdb-core's engine version)
• Expose chdb.core_version — the chdb-core pip-package version (via importlib.metadata)
• Update pyproject.toml to include chdb as a namespace package (namespaces = true)

How it works

The shim chdb/datastore.py is installed into site-packages/chdb/ alongside chdb-core's files. On import it:

1. Reads chdb-core pip-package version → chdb.core_version
2. Patches chdb.__version__ / chdb.chdb_version from the chdb pip-package metadata
3. Replaces itself in sys.modules with the real top-level datastore package

After import:

import chdb.datastore as pd

chdb.__version__      # chdb pip-package version, e.g. "3.7.0"
chdb.core_version     # chdb-core pip-package version, e.g. "26.1.0"
chdb.engine_version   # ClickHouse engine version, e.g. "26.1.2.1"

Test plan

• from chdb import datastore as pd — works, all public API accessible
• import chdb.datastore as pd — works
• chdb.__version__ shows chdb pip-package version
• chdb.core_version shows chdb-core pip-package version
• chdb.engine_version unchanged (ClickHouse engine version)
• No double-patching when both code paths trigger