Expose alarms and travel time in event output

[schappim]

Why

A user reported that ekctl calendar update doesn't update an event's notes. It turned out they were on v1.2.0, which has no update subcommand at all — but chasing it surfaced a real gap: --alarms and --travel-time are write-only. Nothing in the event JSON reflects either, so there's no way to confirm from the CLI that they applied.

hasAlarms looks like it serves that purpose but doesn't. Calendars apply a default alarm to new events, so a freshly created event reports hasAlarms: true with an alarm nobody asked for.

What

Adds alarms and travelTimeMinutes to the event dictionary, so they flow through show event, list events, add event, and update event in json, csv, and text.

Rendered in the same units the flags accept, so output round-trips into input:

"alarms": [
  { "type": "relative", "minutesBeforeStart": 10 },
  { "type": "relative", "minutesBeforeStart": -15 },
  { "type": "absolute", "date": "2026-02-15T08:00:00+11:00" }
],
"travelTimeMinutes": 20

--alarms "10" reads back as 10; --alarms "+15" as -15. Alarms created outside ekctl can be absolute, hence the type discriminator. Empty alarms render as [] and unset travel time as null, matching how attendees and location already behave.

Also: a latent crasher

Guarded both existing KVC writes to the undocumented travelTime property with responds(to:). KVC against a key the class doesn't define raises NSUnknownKeyException — an Objective-C exception Swift cannot catch — so if Apple ever drops the property, the existing unguarded setValue would hard-crash the CLI. Adding a read doubled that exposure. --travel-time now returns a clear error instead.

Testing

9 new unit tests (146 total, all passing): before/after/at-start offsets, absolute alarms, nil and empty, sub-minute offsets rounding rather than truncating, and a round-trip test asserting AlarmParsing.parse → render returns the original flag value.

Verified live against real calendars (created and deleted): --alarms "10,30" --travel-time 20 reads back exactly; --alarms "+15,0,60" renders as -15, 0, 60.

Bumps to 1.6.0.