Verified against backend source at tip 299e409f15 (tui_gateway/server.py).
- SubscriptionCurrent: add cancel_at_period_end / cancellation_effective_at / cancellation_effective_display (emitted by _serialize_subscription_state, were missing on mobile).
- SubscriptionTier: align to wire shape {tier_id, name, tier_order, dollars_per_month_display, monthly_credits, is_current, is_enabled}; old {tier_name, price, currency, interval} never matched the backend and is unused in-app.
- NOTE: usage.bars UsageBar *_display string model is CORRECT — the backend serializes raw *_usd floats to *_display strings via _serialize_usage_bar before sending. Issue #631 misidentified this as a gap; switching to *_usd would break the bars. No change made there.
Co-authored-by: ronia <ronia@m57>
