* `GRIST_ANON_PLAYGROUND`: When set to 'false' deny anonymous users access to the home page
* `GRIST_FORCE_LOGIN`: Much like `GRIST_ANON_PLAYGROUND` but don't support anonymous access at all (features like sharing docs publicly requires authentication)
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Co-authored-by: Florent FAYOLLE <florent.fayolle@beta.gouv.fr>