boom-10/dsh-goal-budget

Sets token, cost and wall-clock caps on a DSH goal and blocks that goal when a cap is reached, instead of only reporting the spend. The figures come from the usage events DSH records for the session, priced per model, with a pill beside the composer that opens a per-model breakdown. The official DeepSeek tariff is built in, with peak/off-peak pricing toggleable because it depends on the route; other models are priced from configured rates, and a model with no rate has its tokens counted and its name listed rather than being guessed at.