LabConfluo: Edit together, even offline

Confluo is a collaborative editor that lets multiple people change the same document and converge to the same result, even offline. It uses per-field last-write-wins registers stamped with Lamport (timestamp, site) clocks, which makes merging commutative, associative, and idempotent - and those convergence laws are exactly what the tests assert. It is a from-scratch, dependency-light build using BroadcastChannel transport and an offline toggle that you can download and run locally.