Dial fresh socket per command; add reactivate DoCommand

[Joseph Borodach (JosephBorodach)]

Summary

• The persistent TCP socket to the URCap stalls reads indefinitely on PolyScope X (UR12e), most reliably after the Robotiq is physically disconnected and reconnected — e.g. a tool changer swapping the attached gripper. The only recovery was restarting the entire module.
• Replace the persistent socket with dial-per-send: every command opens a fresh connection, writes, reads with a 5s deadline, and closes. Add a mutex so concurrent calls don't interleave.
• Add a {"reactivate": true} DoCommand for explicit ACT/GTO/FOR/SPE re-init after the URCap state itself was reset (still required on PolyScope X after physical disconnects, with or without this fix).