Peer-review a teammate's checked-out branch as a thorough reviewer. Use when the user has someone else's PR or branch checked out locally and asks to "review this PR", "review this diff", "do a code review", or "check this branch before I approve". Runs `git diff <base>...HEAD` and surfaces six classes of issue — API/interface design, logic bugs in new code, missing edge cases & error paths, security concerns, regressions to existing behavior, and architecture/coupling problems. Explicitly ignores code style, performance, naming nits, missing tests, missing docs, and bikeshed-able preferences. Produces a severity-tagged markdown report (must-fix / consider / question) gro…
