ARCP v1.1 §9.6. Add `CostBudget` capability with `max`/`unit`/`consumed`. Runtime-enforced. `BUDGET_EXHAUSTED` error. Subset semantics. `Samples/CostBudget/`. Tests. --- Audit reference: [ARCP SDK Audit v1.1 (2026-05-19)](https://gist.github.com/nficano/f68a8ae66477a38eebc70f18044d0d4b)
ARCP v1.1 §9.6. Add
CostBudgetcapability withmax/unit/consumed. Runtime-enforced.BUDGET_EXHAUSTEDerror. Subset semantics.Samples/CostBudget/. Tests.Audit reference: ARCP SDK Audit v1.1 (2026-05-19)