Fix image embedding vectors and index fallback

[FANNG1]

Summary

• Read ChineseCLIP embeddings from pooler_output and validate the configured embedding dimension
• Add pylance fallback when lance_ray distributed index building fails
• Cover normalized model output shapes and index fallback behavior in tests

Validation

• uv run pytest tests/image/test_embedding_pipeline.py tests/workflow/test_index_manage.py -ra
• uv run pytest tests/image -ra
• Ran the real image workflow on data/images, including analyze, ingest, scalar query, manage, analyze --embed, vector index, text query, and image similarity query