* perf(proxy): aggregate daily model usage per flush instead of upserting per request
* perf(proxy): drain queued model usage in the spend log flush job
* perf(proxy): queue model usage at request time instead of writing to the db
* test(proxy): cover batched daily model usage aggregation and retries
* test(proxy): read back model insights written by the batched flush
* fix(proxy): drain the whole model usage queue each flush so it cannot grow unbounded
* test(proxy): give the mock prisma client a model usage queue
* test(proxy): cover draining a model usage queue larger than one spend log batch
