Create a persistent HeyGen avatar — a reusable face + voice identity for the agent,
the user, or any named character — powered by HeyGen Avatar V technology.
Prompt-based creation by default (description → HeyGen builds it); photo upload is
optional for real-person digital twins.
Use when: (1) giving the agent a face + voice so it can present videos
("bring yourself to life", "create your avatar", "give yourself an avatar",
"design a presenter", "set up an avatar", "let's make an avatar"),
(2) the user wants to appear in videos as themselves ("create my avatar",
"I want my face in a video", "digital twin of me", "build me an avatar"),
(3) building a named character presenter ("create an avatar called Cleo",
"design a character named X"), (4) establishing HeyGen identity before making videos —
the correct FIRST step when no avatar exists yet.
Chain signal: when the user says both an identity/avatar action AND a video action in the same
request ("create an avatar AND make a video", "set up identity THEN create a video",
"design a presenter AND immediately record"), run heygen-avatar first, then heygen-video.
Returns avatar_id + voice_id — pass directly to heygen-video to create HeyGen videos.
NOT for: generating videos (use heygen-video), translating videos, or TTS-only tasks.