fix(deps): make OCI dependencies optional on release 0.6

[skamenan7]

Summary

• remove OCI-related packages from default package dependencies on release-0.6.x
• expose them through the explicit oci extra instead
• add tests that guard default/starter installs while preserving explicit OCI provider deps

Before / after proof

Built wheel metadata from v0.6.0 before the fix advertised OCI dependencies unconditionally:

Requires-Dist: oracledb>=3.4.1
Requires-Dist: oci>=2.165.0
Requires-Dist: numpy>=2.3.2

Built wheel metadata after this fix advertises them only behind the oci extra:

Provides-Extra: oci
Requires-Dist: numpy>=2.3.2; extra == "oci"
Requires-Dist: oci>=2.165.0; extra == "oci"
Requires-Dist: oracledb>=3.4.1; extra == "oci"

Test plan

• uv run --locked --group unit pytest tests/unit/distribution/test_list_deps_output.py -q
• env UV_CACHE_DIR=/tmp/uv-cache-ogx-oci-main UV_PYTHON_INSTALL_DIR=/tmp/uv-python-ogx-oci-main uv build --wheel