feat(rag/store): add OceanBaseStore as a vdb choice

[PsiACE]

AgentScope Version

The main branch of AgentScope

Description

This PR implements OceanBaseStore using the pyobvector library. And align OceanBaseStore API behavior with MilvusLiteStore for consistency

Support for 3 distance metrics: COSINE, L2, IP (Inner Product)

Testing

# Requires OceanBase or SeekDB running
docker run -p 2881:2881 -d oceanbase/seekdb:latest
# Set envs
export OCEANBASE_URI="127.0.0.1:2881" && export OCEANBASE_USER="root" && export OCEANBASE_PASSWORD="" && export OCEANBASE_DB="test"
# UT
pytest tests/rag_store_test.py::RAGStoreTest::test_oceanbase_store -v
# e2e examples like MilvusLiteStore
python examples/functionality/vector_store/oceanbase/main.py

Checklist

Please check the following items before code is ready to be reviewed.

• Code has been formatted with pre-commit run --all-files command
• All tests are passing
• Docstrings are in Google style
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

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[PsiACE]

The examples are kept to demonstrate that the API constraints align with MilvusLiteStore. They can be removed if needed.

The unittest workflow is not updated yet. We can evaluate the gap before merging.