We should implement Full Async Support for YDB Vector Store Integration

[murathany7]

YDB supports asynchronous operations via ydb.aio.Driver, and adding full async support would allow this vector store integration to work efficiently in asynchronous applications without blocking the event loop.

Planned improvements:

• Use ydb.aio.Driver for async connections

Add async equivalents of key methods:

• _execute_query

• similarity_search

• similarity_search_with_score

• similarity_search_by_vector

• add_texts

• delete

This will bring the integration in line with modern Python async best practices and enable smooth usage in async workflows.

I’ll be implementing this.