feat(tradein): brand-by-account + result IA redesign (distinct asking/sale prices)
- Resolve brand from account: /me returns brand (praktika/kopylov->praktika);
useBrand uses ?brand= param OR me.brand (param wins) -> praktika auto-branded
on login (no manual ?brand= needed).
- Result IA (Brusnika-style): single «Ожидаемая цена сделки» headline (lower,
-X% vs asking, 5-12% note); two DISTINCT reference figures (asking объявления
vs ДКП Росреестр) + price bars; sources row; 3 always-on explainer cards
(asking!=real, ремонт по состоянию, скрытые расходы <=15%).
- Defer commercial buyback value (Brusnika p.4): OfferCard stub + TODO, no
invented numbers (pending Praktika commercial terms).
- tsc clean, ruff clean, 35 backend tests (7 new /me-brand).
Refs #657
95bada3855