feat(web): info icon on every param with hover/click tooltip; add help text to all params

feat(models): expand chatterbox-en params (seed, repetition_penalty, min_p, top_p)

feat(api): adapter generate returns seed_used; expose X-Seed-Used header

feat(api,models): FastAPI app with /api/health, /api/models, activate, /api/generate + chatterbox-en adapter