Clean up dead code: embed_texts and hybrid_search

[adinschmidt]

Summary

There are currently unused public APIs with #[allow(dead_code)]:

• embed_texts in src/embeddings.rs
• hybrid_search in src/lancedb.rs

Proposed change

• Either:
  • remove these functions, or
  • wire them into the CLI (e.g. batch embeddings, optional hybrid search mode).

Acceptance criteria

• No #[allow(dead_code)] needed for these items
• Behavior is documented (CLI help or README) if kept