v0.13.0

Fixed

• A Gemini 2.5 request that ran several Google Search queries is charged one grounding fee. Gemini 2.5 bills Search
  grounding per grounded prompt ($35 / 1,000), Gemini 3 per search query ($14 / 1,000); CalculateCost multiplied both by
  the number of calls, so a 2.5 request with three queries cost three fees. The 0.9.0 entry below calls both prices «per
  1,000 grounded prompts» — the 3.x price is per query.

Changed

• Breaking — a tool fee says what it counts. ToolCallPrice.Unit (ToolFeeUnit.Call — every call the response
  reports, the default; ToolFeeUnit.Request — once per request that used the tool), and PricePerThousandCalls is
  renamed PricePerThousand. CalculateCost applies the unit; TokenCounts.ToolCalls stays the count the response
  reports. Migration: read PricePerThousand instead of PricePerThousandCalls; a fee you build yourself is per call
  unless you set Unit.