add: configurable auto-resume limit

[lollipopkit]

Hi, this commit:

• add maxAutoResumeTurns to autoresearch.config.json
• keep the existing default auto-resume safety limit at 20
• document the new config option and add focused config tests

Thanks for your CR :)

[davebcn87]

@lollipopkit Could you share more details on specific use cases where 20 was not big enough? Instead of making this configurable I'm thinking if extending that number for long sessions automatically would make sense.

[lollipopkit]

I have use cases with hundreds of iterations.

If we switch to auto-extend, what's the stopping criterion?

• Consecutive n discards (excluding crashes and check_failed)? With n decided by the LLM?
• Rate of improvement staying below n over the last 10 iterations? Again, n decided by the LLM?