Reads ZCode CLI usage from ~/.zcode/cli/db/db.sqlite. The model_usage
table has exact per-request tokens; cost is computed from the pricing
table since ZCode stores none (GLM-5.2 runs on the z.ai start-plan
subscription).
- Split cached tokens out of input_tokens (OpenAI-style) so fresh input
and cache reads price correctly
- Attach each turn's tool calls to one request to avoid double-counting
- Map GLM-5.2 to glm-5p1 (GLM-5.1 rate) until LiteLLM lists it
- Register as a lazy SQLite provider; add test and provider doc
