* feat(oneshot): add --usage-file JSON usage report to hermes -z
Pipelines driving hermes -z (batch reviewers, cron scripts, eval
harnesses) had no way to account for per-invocation spend: the agent
computes estimated_cost_usd and full token counts internally, but
oneshot mode discards everything except the final response text.
- hermes -z PROMPT --usage-file PATH writes a JSON report after the
run: estimated_cost_usd, cost_status/source, input/output/cache/
reasoning/total tokens, api_calls, model, provider, session_id,
completed, failed.
- Written even when the run fails (with a failure field) so callers
can always account for spend; the write itself is best-effort and
never masks the run's own outcome.
- Flag registered in both the full parser and the Termux fast path;
added to both value-flag scan sets so profile detection stays
correct.
Validation: 6 unit tests + live E2E (real -z run produced a report
with real OpenRouter cost + token counts).
* test: include usage_file kwarg in oneshot dispatch assertions
The two dispatch tests assert the exact kwargs dict passed to
run_oneshot; the new usage_file kwarg must appear there.
