Unlinked spawn detection.
Flags calls to erlang:spawn/* (without _link or _monitor) that create
processes with no supervision or failure propagation link. These "orphan"
processes silently disappear on crash.
Uses only layer 1 facts (spawn_call with variant field).
Output relations
unlinked_spawn(func, id)— function and instruction where a bare spawn occurs.
Finding severities
unlinked_spawn—:warning. The spawned process may be deliberately fire-and-forget, but its crashes are invisible: no link, no monitor, no supervisor ever observes them.