Callr Actions: play@v2 plays audio files by SID

The new play@v2 action plays an audio file from your library using its SID, the same identifier the REST API v2 uses (/v2.0/audio-files/{sid}). You no longer need the legacy numeric ID.

- action: play@v2
  params:
    sid: '0d0f9ef6'

sid is required: 8 lowercase alphanumeric characters. Quote it in YAML, because an all-digit SID would be parsed as a number. Uppercase values are accepted.
The file must belong to your account (or be a Callr system file) and be ready to play.
Optional stopOnTalk interrupts the audio when the caller speaks. It works like say@v2:
```
stopOnTalk:
  enabled: true
  minWords: 2
```
Speech detection uses speech-to-text and is billed like say@v2 when enabled. Set language to match the caller.
Result: { ok: true, stoppedOnTalk: true|false }.
Keypresses do not interrupt play@v2. Use gather@v3 to collect digits.
Maximum playback time is 30 minutes.
If the SID is unknown or the file isn't ready, the scenario ends and the error appears in the run log (audio file not found / audio file not ready).

play@v1 (numeric ID) is unchanged and not deprecated.

See the Callr Actions reference.