FX.22 BimCraft: dragging a wall no longer skews the room, and Square up brings 90 degrees back

Discord report with screenshots: dragging a wall's centre grip slightly off square tilted both joined walls, and nothing brought the room back to 90 degrees. The grip moved the wall by the whole drag and carried the joined corners with it; Length did the same.

Changed in the lab build. The centre grip moves the wall square to itself; its corners slide along the joined walls, so they keep their angle at any angle, and partitions butting into it come along. Ctrl (Cmd) gives the old free move. An end grip catches square to the wall joined at its other end within 3 degrees (Shift stays on the plan's axes, as before). Properties for a straight wall adds: Measure from (centre line, inside face, outside face), which Length and the new Room size read and set from; Move square (typed, + out, - in); Angle to joined wall (or Direction for a wall on its own); and Square up, which turns the connected walls within 10 degrees of a right angle to their main direction. A distance can be typed while a grip is held (Enter or letting go uses it, Esc drops the move). Each change is one undo step. Geometry in wall-square.js.

Tested: tools/bimcraft-test/wall-square-test.mjs 56, browser-wallsquare.mjs 28 (the report's steps), browser-model, browser-comforts and --model pass. Not tested: a real project with many walls, doors in a wall whose corners slide at a non-right angle, or a desktop build.