(Having another stab at this one….)

The logline has one major fundamental problem which I simply can't find a solution for - the MC can't do anything except wait in order to achieve her main goal - this isn't very cinematic (if at all...).

After reading your logline, and getting rid of the clutter, I believe your logline needs that one extra thing.

You say, she 'must withstand'? but that's a passive action. Lead characters are pro-active, they have a plan of actions.

How does your lead character cope with her anti-social cellmate? What is her plan?

For instance, does she lie and pretend to be a big-time criminal?
Does she act crazy?
Does she pick a fight with the toughest prisoner to show she is serious?

What's your lead characters plan of action?

I am going to try to reduce the word count to see what we have:
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"When an addicted high-end escort is arrested, she is incarcerated with an anti-social cellmate."