Folds durable provider_usage events from .pixir/sessions/*.ndjson and emits
prompt-cache family accounting as JSON.
Usage:
mix pixir.cache.reconcile
mix pixir.cache.reconcile --sessions-dir .pixir/sessions
mix pixir.cache.reconcile --helpThe task is offline-only. below_minimum_count records expected Anthropic pa1 calls
where a cache plan existed but both creation and read counters were zero (for
example, below the 512-token minimum cacheable prefix).