Introduce error guard with 6 tries and successful exec reset

[imas234]

• Kept total agent turns max limit, but increased it to 20
• Kept the edit limit because my understanding is it forces a fresh rewrite after that limit, not just stop agent turns
• Added required error retry limit at 6

[imas234]

Addresses #29 to the extent that we have a larger max agent turn limit + more safeguards.

However, if we fully want to not have a max limit, that is a separate conversation. Sufficiently large tasks will eventually hit this new larger limit.