[Feature]: Set, modify, or delete an Alexa alarm from Home Assistant

### Is your feature request related to a problem? Please describe.

There is currently no way to set, modify, or delete an Alexa alarm from Home Assistant without going
through the `media_player.play_media` action with `media_content_type: custom`. This routes the
command through Alexa's voice/NLU pipeline, which always triggers a spoken confirmation
(e.g. "Okay, alarm is set at 9 o clock") — regardless of volume level or Do Not Disturb state.

This makes it impossible to build a fully silent "smart alarm clock" automation, e.g. for shift
workers who need a different wake-up time set automatically every day depending on their shift
schedule. ioBroker's Alexa adapter has a dedicated "Add new Alarm" datapoint for this that
does not go through voice/TTS at all.

### Describe the solution you'd like

A native service (e.g. `alexa_media.set_alarm`) that talks directly to the Alexa alarm API endpoint
(the same one the sensor/next_alarm data already comes from), with parameters like:
- `entity_id` / target device
- `time` (and optionally `recurrence`/`label`)

This should not go through the voice command pipeline and therefore should not trigger any spoken
device response.

Ideally also:
- `alexa_media.delete_alarm` (to remove/replace an existing one, e.g. by alarm id from the
`next_alarm` sensor's attributes)
- `alexa_media.enable_alarm` / `disable_alarm` (toggle without deleting)

### Describe alternatives you've considered

- `media_player.play_media` with `media_content_type: custom` and the phrase "Set an alarm for 8 o clock" — works, but always causes an audible spoken confirmation with no way to suppress it
(tried volume 0, tried Do Not Disturb — device still speaks).
- Enabling "Brief Mode" ("Short Mode") in the Alexa app — reduces the response to a short tone
instead of a full sentence, but does not fully silence it.
- No way found to toggle/enable individual pre-created alarms from HA either (no matching switch
entity), so pre-creating alarms for each shift and just toggling them isn't currently possible.

### Additional context

Alexa already exposes alarm data to this integration read-only via the `next_alarm` sensor, so the
underlying API access clearly exists — this request is about extending that to write access.