when someone gifts subscriptions.

### User Information
- `[[[event.user_id]]]` :: Gifter's Twitch ID
- `[[[event.user_login]]]` :: Gifter's username
- `[[[event.user_name]]]` :: Gifter's display name
- `[[[event.user_avatar]]]` :: Gifter's profile image URL

### Gift Data
- `[[[event.total]]]` :: Number of subs gifted
- `[[[event.tier]]]` :: Sub tier (1000, 2000, 3000) :: DON'T USE
- `[[[event.tier_display]]]` :: Sub display (1, 2, 3) :: USE THIS
- `[[[event.cumulative_total]]]` :: Total gifts ever
- `[[[event.is_anonymous]]]` :: true/false if anonymous

note: maps to the Twitch EventSub event `channel.subscription.gift`. Overlabels collapses gift bombs (multiple gifts from the same user within an 8-second window) into a single alert; use `[[[event.total]]]` for the combined count.