* fix(agents): reject synchronous sessions_send self-targets, break down missing-cost entries, dedup usage merges
- sessions_send fails fast with a clear error when a synchronous send resolves
to the calling session's own key, instead of enqueueing behind the sender's
own lane until timeout and falling back to an empty reply; fire-and-forget
(timeoutSeconds: 0) self-delivery keeps working (#107172)
- missingCostEntries now carries a provider/model breakdown surfaced on the
status runtime line and gateway CLI cost line, so zero-priced usage (e.g.
openai-codex/*) is attributable instead of an opaque counter (#98348)
- codex-synthetic-usage merge helpers share one precedence helper; behavior
unchanged, duplicate ranking logic deleted (#107497)
* test: use a valid billing type in synthetic-usage precedence case
* test: fix billing expectation to match valid type
65188a7430