Resolve preview URL for a quiz

Build a public URL to open a quiz on the project's primary host (project's custom domain if set, otherwise {project_id}.web2wave.com). Works for any quiz — no need for the API caller to know the project's subdomain. Use this from MCP / scripts instead of guessing the host.

Modes:

• no version arg → returns the currently published version if published_version is set, else the live draft;
• version=latest-published → forces the published version (auto-fills the encoded version hash from the published version's date);
• version=<int>-<base64date> → returns that exact archived version;
• any other string → passed through as-is.

Other params: screen_id (jump to one screen), locale, theme, edit_mode=1, project_domain (override the host explicitly).