Add an automated second code review to CI

Came out of an ideation session, not a scoped request.

The idea is to run an automated code review tool on pull requests as a second pass alongside human review, so that regressions and quality issues get flagged before anyone reads the diff. Which tool to use is an open decision and is shared by both places this should land — pick it once here, then apply it in each.

It applies in two independent places: this repository's own pull requests, and the CI workflow that ships inside every generated project.

- [ ] Run an automated code review on gonext's own pull requests
- [ ] Ship an automated code review step in the generated project's CI workflow

Start by locating the CI workflow for this repository and the CI workflow shipped in generated projects. Resolve the open choice of automated review tool before implementing it in both independent locations. Done means both workflows run the same review step on pull requests and the two checklist items can be verified.

Written by the indexing model from the issue text.