[FEATURE]: code critic

[Githubguy132010]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

I would like a code critic agent built into opencode that checks the main agents work. The critic looks at the goal (prompt) and checks the code and tests the app if applicable to check if the goal is reached with the current implementation. If not, start a subagent to fix the code review issues. Then run the critic again. This loops for a configurable amount of turns or until there are no issues. The critic should be a subagent.