Replace the free-text username input with a Select populated from a new
/sharing/users endpoint. Users already on the target's share list are
filtered out, and the trigger surfaces loading / empty states. Matches
the existing permission model since sharing only ever required knowing
a username.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
dtoro
967cf23b82