Implement updates on JMAP for Calendar syntethic ids

### Discussed in https://github.com/stalwartlabs/stalwart/discussions/2923 <div type='discussions-op-text'> ^{Originally posted by **rathlinus** March 22, 2026} Stalwart expands recurring events into instances with synthetic IDs, but CalendarEvent/set rejects any update or destroy targeting these IDs with "not yet supported" errors. This means clients cant edit or delete individual occurrences of a recurring event through the IDs that Stalwart itself provides. Updates to a synthetic ID should apply as recurrenceOverrides on the master event. Destroys should set excluded:true for that instance. Both should trigger iTIP scheduling when applicable. This affects any JMAP client doing standard calendar operations like "delete just this occurrence" or "change the title of one meeting."</div>