docs:add array type support

[XuQianJin-Stars]

Summary

Add comprehensive documentation for Arrow data types support in Lance, with a focus on array types for vector embeddings - the most important use case for Lance integration.

This PR addresses the feedback from the community that the Lance documentation was missing array/vector type support documentation. See: https://fluss.apache.org/docs/next/streaming-lakehouse/integrate-data-lakes/lance/

Changes

• Add new docs/src/guide/data_types.md covering:

  • Complete Arrow type system overview (primitive, string, binary types)
  • Array types for vector embeddings (FixedSizeList, List, LargeList)
  • Python and Rust code examples for creating and using vector embeddings
  • Vector search examples with index creation
  • Nested and complex types (Struct, Map)
  • Data type mapping table for integrations with Flink, Spark, Presto, etc.
  • Best practices for vector data storage and retrieval

• Update docs/src/guide/.pages to include the new Data Types page in navigation

Why This Matters

Vector embeddings are the primary use case for Lance integration with streaming systems like Apache Fluss. The existing documentation lacked:

1. Clear explanation of how to use ARRAY<FLOAT>(n) / FixedSizeList for vectors
2. Type mapping table showing array type support
3. Practical examples for ML/AI workflows

This documentation fills that gap and helps users understand how to properly store and query vector embeddings in Lance.

[github-actions]

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