Dragonframe's Arc motion control adds DUCO, DOBOT and Fairino cobot arm support

Dragonframe's public development-branch changelog has widened Arc, the motion-control workspace, beyond the Universal Robots six-axis arm support it added in July: the 2027.01 branch's own summary line now reads "Arc: Supports some cobot robotic arms from Universal Robots, DUCO, DOBOT, and Fairino." DOBOT and Fairino integration land in build 2027.01.18516 and DUCO integration in build 2027.01.18560, with a shared fix two builds later ("Fairino and Dobot attempt to clear soft limit errors automatically") showing the same actively-debugged, hardware-driven pattern as the original UR support. As with UR in July, the changelog names no shipped production using any of the three newer cobot brands -- this is a capability addition, not a production credit. Folded into the Wiki's dragonframe-arc-motion-control page.

[Update 2026-09-29] Later 2027.01 dev builds move the four-brand cobot support from integration to tuning. Build 2027.01.18748 fixed pan/tilt/roll conversion for Fairino, DUCO and DOBOT, and 18749 improved their loop timing. Build 18960 reads: "Dragonframe now uses the virtual configuration's nodal offsets as the robotic arm tool offset"; the same build raised Fairino's update rate from 125Hz to 250Hz. Builds 18976 to 19010 then harden the connections: an updated Universal Robots SDK network teardown, a Fairino initialisation change "to prevent long hangs", UR's Primary Interface (port 30001) made optional but "required for setting the nodal offsets", and a new UR script that must be installed on the arm itself. Nodal offsets are now sent only when at least one is non-zero, and Fairino's apply to the currently active tool. Folded into the Wiki's Arc page.