refactor(ui): drop v16 legacy tab

feat: add title proofreading sandbox tab

ui: surface v24 tab first (default), v16 legacy second

ui: remove per-tab description blurbs

feat: add v24 pipeline (FT + self-consistency × 2 + tool-calling judge)

Single-tab feedback UI (Good/NotBad/Critical); FT dedup tighter

Move blindtest tab first; add RLS policies and error surfacing

initial deploy