- Add PerGatewayUsage interface and buildPerGatewayUsage() function
- Each gateway's most constrained limit shown independently, sorted by exhaustion
- Per-account rows render BEFORE aggregate summary
- Aggregate cards labeled 'Combined' when multiple gateways exist
- 'Soonest reset' and 'Combined limit' labels replace misleading single-gateway labels
- Filter out gateways with no configured limit to reduce noise
- Add typed limit fields to RuntimeUsageCurrent: output_token_limit,
total_token_limit, message_limit with matching pct and source
- Add total_output_tokens and output_tokens_per_minute to burn rate
- _build_current() now computes each pct from matching units only
- Legacy token_limit backfilled from typed limits for backwards compat
- Frontend aggregateRuntimeUsage() tracks typed limits separately
- limit_kind field on predictions indicates which limit drove time-to-limit