One-time (but safely re-runnable) setup flow that scaffolds a project's aw-tester aw-target: detects auth strategy, captures storage state, writes .claude/aw-targets/<target>.yml, and validates with a smoke spec. `--target local` (default) scaffolds the local dev target; `--target preview` scaffolds the PR-preview target ui-verify runs against (and is what `/ui-verify setup` delegates to). Also records the repo's UI surface (what counts as a UI change) so the is-ui-diff gate is accurate per repo, and the preview auth profile. Re-runs detect the existing aw-target and only re-prompt for what broke or changed. Triggers on "/aw-setup", "setup aw-tester", "scaffold aw-target".