FX.137 Arc: all ten methods (3-Point, Start/Center/End/Angle/Length, Start/End/Angle/Direction/Radius, Center/Start/End/Angle/Length) and Continue

The Arc tool only offered a start point or a centre. Now every method is there, in CadCraft, ModelCraft, PartCraft sketches, MarkupCraft and TakeoffCraft, from one shared library (lib/arcs, copies via tools/arcs/sync.mjs). Arcs run counter-clockwise; a negative angle or chord length takes the clockwise arc, a negative radius the major arc. Angle, length, radius and direction can be clicked or typed. CadCraft also has Continue (Enter at the start point) tangent to the last line, arc or polyline, and a split button listing the methods. MarkupCraft and TakeoffCraft keep their saved arc formats; PartCraft arcs stay centre/start/end so constraints work. Tests: tools/arcs/test.mjs, test-cadcraft, test-markupcraft, test-takeoffcraft, tools/partcraft-test/test-sketch-arcs.mjs, tools/modelcraft-test/tools07.mjs. Not yet checked by hand in a browser: MarkupCraft and TakeoffCraft pointer flow, PartCraft split face label, ModelCraft on a tilted face.