Schedule fields

JSON / MCP	CLI	Behavior
`run_in`	`--run-in`	Fire once after a duration such as `5m` or `2h`.
`run_at`	`--run-at`	Fire once at a future RFC 3339 instant.
`every_seconds`	`--every-seconds`	Repeat on a fixed interval of at least one second.
`time_of_day`	`--time-of-day`	Repeat at a local `HH:MM` time.
`days_of_week`	`--days-of-week`	Required with `time_of_day`. Use `all` for every day, or provide a non-empty selection of three-letter names: Sun, Mon, Tue, Wed, Thu, Fri, Sat.
`timezone`	`--timezone`	IANA timezone for `time_of_day`; defaults to `UTC`.

{% if timer_schedule_optional %} Omit all schedule fields to preserve the current schedule. When replacing it, provide exactly one of {% else %} Provide exactly one of {% endif %} run_in, run_at, every_seconds, or time_of_day. API and MCP callers may omit schedule_kind and let the server infer once or interval; the CLI always infers it from the schedule flag.