Cleaner diffs and cheaper mechanical phases

A cleanup pass strips AI slop before verification, and mechanical phases run on smaller models by default.

Added

A cleanup stage strips needless comments, dead code and over-defensive scaffolding before verify grades the diff
Lint autofix runs before verify, using your fix command or an agent that finds the project’s fixers
Build prompts steer agents toward lean, human-like code
Trau flags tickets whose spend did not match their size