Consider setting R_CONFIG_ACTIVE environment variable to "shinylive"

[gadenbuie]

In posit-dev/r-shinylive#45 we briefly discussed adding environment variables to signal that an app is running on shinylive.

In that issue I mentioned considering setting R_CONFIG_ACTIVE, which is used by the config R package and is often used by Shiny apps to choose setting based on context.

Regarding environment variables, another interesting option to consider is setting R_CONFIG_ACTIVE to something like "shinylive" in a shinylive context. This env var is consulted by the config package and is set by Posit Connect.