An invite may carry its own mail, with the form's fields and a spoken date and time

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/memberships.rs

@@ -254,6 +254,8 @@ pub async fn grant(state: &crate::server::AppState, group: &str, name: &str, who
         reset_link: None,
         link_expires_ms: None,
         created,
+        mail: None,
+        fields: Default::default(),
         already_member: !created,
     };
     match existing {