Function scoped_uid 

pub fn scoped_uid(uid: &str, scope: Option<&str>) -> String

Build the id component of a ticket [RecordKey]: the bare uid, or "<scope>/<uid>" when a board/connection discriminator is supplied.

The id is stored as a single opaque, reversibly-encoded path segment (gonzalo_core::segment), so an embedded / is escaped rather than nesting directories; two distinct scope+uid pairs therefore never collide. Kept as a standalone helper so downstream lookups (e.g. ticket get) can reconstruct the exact scoped id without a Ticket in hand.