fix(search): preserve zero FT.CREATE scores

[alencristen]

Description

FT.CREATE dropped SCORE: 0 because the parser used a truthy check. Redis accepts zero, so this forwards it and adds a regression test.

Checklist

• Search tests pass (272)
• Lint, build, and command JSDoc checks pass
• No docs change needed

Full suite: 3,313 passed; one unrelated socket timeout test timed out under load and passed alone.

Assisted by OpenAI Codex (GPT-5.6).