Open Orbit briefing skill — selected by the Orbit pipeline when
Gmail is the user's only connected connector, or when the user
explicitly scopes their daily digest to Gmail. Pulls the past 24
hours of inbox activity (replies awaited, mentions, cc, auto-
categorized bulk) from the user's authenticated Gmail connection
and renders the digest as the Orbit Daily Digest email opened
inside Gmail's reading view. This skill should not be triggered
manually — it is invoked by Orbit's daily-digest scheduler against
live Gmail data.
