This PR reworks our existing billing code in preparation for charging
based on LLM usage.
We aren't yet exercising the new billing-related code outside of
development.
There are some noteworthy changes for our existing LLM usage tracking:
- A new `monthly_usages` table has been added for tracking usage
per-user, per-model, per-month
- The per-month usage measures have been removed, in favor of the
`monthly_usages` table
- All of the per-month metrics in the Clickhouse rows have been changed
from a rolling 30-day window to a calendar month
Release Notes:
- N/A
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Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Richard <richard@zed.dev>
Co-authored-by: Max <max@zed.dev>
