feat: tab completion for citation keys (from feat/tab-completion) (#121)

from `feat/tab-completion` to`main`.

Tested on staging. Functionality works as expected. Latency increased
from 2s to 5s, but I suspect it's because the API key was at the brink
of having no credits left. Will look into the latency more.

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Co-authored-by: Junyi <hji200914@gmail.com>
Co-authored-by: 4ndrelim <tiltedaf3@gmail.com>

Author: 3 people