v0.58.1

Fixed

• Fix Google Calendar outbound sync failing for timed and recurring events. Oikos stores timed events without seconds (YYYY-MM-DDTHH:MM), but the Google Calendar API requires RFC 3339 datetimes with seconds — timed events were rejected with "Bad Request" and recurring events surfaced the malformed start as "Invalid recurrence rule". Outbound events now emit seconds, and recurrence UNTIL values are coerced to the type Google requires: a plain DATE for all-day events and a UTC date-time for timed events.