docs(sessions): show closing AsyncSQLiteSession

[00200200]

Summary

This pull request updates the AsyncSQLiteSession example to close the session after the final run and documents the lifecycle boundary of close(). The example now releases its owned aiosqlite connection instead of leaving it open.

Test plan

• make build-docs
• Existing generated reference files were unchanged.
• No live model or API calls were made.

Issue number

Not linked to an existing issue.

Checks

• Verified the documentation example and affected implementation behavior.
• Confirmed the documentation build passes.