is_dep_floor_mismatch_muted

Return whether this checkout's muted fingerprint matches fingerprint.

Reads without taking the store lock. Writes land via an atomic Path.replace, so a concurrent mute is either wholly visible or wholly absent — never torn. Locking here would instead put a filelock import and a 5-second timeout on the startup path of every editable launch, and a second dcode mid-write would stall this one for no benefit.