Billing (Usage Tracking): foundations

Status

superseded — esta RFC foi arquivada em 2026-05-15. O koder-billing em services/foundation/billing/engine/ já entregou AI billing em v0.3.0 (2026-03-26): POST /api/v1/ai/usage/events, pricing built-in pra 25+ modelos (OpenAI, Anthropic, Google, Meta, Mistral, DeepSeek) com cache discount + markup 20%, quotas per-org, spend alerts, dashboard tab "AI", tables ai_usage_eventsai_quotasai_alert_rules. O sector skeleton services/ai/billing/ foi removido (5 tickets de impl nunca tocados); registry component-names.md confirma Koder Billing → services/foundation/billing → kbilling como sole owner. Sectors `services/ai