1. What is the goal of this PR?

• make the crux extraction step optional
• match crux prompting logic to other pipeline steps (so users can see & override the prompt)

2. What specific parts of T3C are you changing and how?

• moved crux logic to match other prompt instructions
• tried to add a checkbox — ideally we'd check the value of this checkbox and only run the crux extraction step if a user actively checked that box

3. How did you test these changes?

• working so far on localhost
• need to figure out how to correctly set the default value to false and pass it through to workers.ts if the user checks the box