Add hybrid search tutorial

[mauvo]

What changed

• Adds a Hybrid search page to the embeddings and vector indexes tutorial.
• Explains when hybrid search is useful compared with semantic/vector search alone.
• Adds a full-text + vector example over the recommendations movie dataset using reciprocal rank fusion.
• Adds the page to the Query navigation and introduces lexical vs semantic search in the tutorial introduction.

Validation

• Downloaded recommendations-embeddings-aligned-5.26.dump and loaded it into neo4j:2026.01-enterprise.
• Validated the example against 9125 movies and 9083 movie embeddings with 1536 dimensions.
• Ran the hybrid Cypher query live with moviePlots and movieText indexes online.
• git diff --check
• npm run clean && npm run build:preview

[mauvo]

@stefano-ottolenghi it won't less me add you as a reviewer. But I guess you're probably the right person to review. :-)

[neo4j-docops-agent]

This PR includes documentation updates
View the updated docs at https://neo4j-docs-genai-tutorials-13.surge.sh

New pages:

• Hybrid search

Updated pages:

• Introduction