Self-contained brief for the frontend implementation session: current
state (slice 1 done, /api/scenario live, parity page to be replaced),
the normative pointers (ui-spec.md, approved mockup), method (drive
Vue fast, the design bar and how to self-check against it with
headless screenshots, tmux dev stack, per-slice commits, a11y as you
go), the four remaining micro-choices to batch into one question
round, and first steps.
