feat: support blob v2 multi-base writes

[everySympathy]

Summary

Adds BlobV2 multi-base write support to daft-lance so callers can write blob columns against explicit base locations instead of assuming a single dataset-local blob base.

Changes

• Adds write-path support for BlobV2 initial_bases, target_bases, and base_store_params.
• Normalizes base ids before constructing Lance BlobV2 arrays.
• Threads base-store configuration through the read/write integration points needed by the data sink.
• Extends BlobV2 write coverage with multi-base scenarios.

Testing

• uv run --python /usr/bin/python3.11 pytest tests/io/lancedb/test_lance_blob_v2_write.py -q
  • Result: 11 passed, 1 skipped
• Lint/type checks for touched files passed locally.

Notes

This PR is scoped to BlobV2 multi-base writing and the corresponding parameter plumbing. It does not change compaction, cleanup, or add-column behavior.