ui: assorted polish - Vue async fix, OrbitControls passive listeners, path-viewer + motor-view + indicators

- main.js: disable Vue async batching so reactive writes from
  hashchange listeners propagate synchronously (matches Vue 1's older
  default; avoids dropped DRO updates).
- orbit.js: pass {passive:false} to wheel/touch listeners so
  OrbitControls.preventDefault() actually suppresses page panning.
- path-viewer: opaque dark canvas (no flash from page background),
  zero-size guard, ResizeObserver cleanup on destroy.
- motor-view: stop clobbering user edits with controller state.
- estop/indicators/tool-view/path-viewer pug: rename FA4 icons to FA6,
  add viewBox to estop SVG, fix tool-view trailing newline.

src/js/orbit.js

@@ -683,12 +683,16 @@ const OrbitControls = function(object, domElement) {
         event.preventDefault();
     }
 
+    // Chrome treats touch/wheel listeners as passive by default,
+    // which prevents OrbitControls.preventDefault() from suppressing
+    // page panning while interacting with the 3D viewer. Pass
+    // {passive: false} on the events that need to call preventDefault.
     scope.domElement.addEventListener("contextmenu", onContextMenu, false);
     scope.domElement.addEventListener("mousedown", onMouseDown, false);
-    scope.domElement.addEventListener("wheel", onMouseWheel, false);
-    scope.domElement.addEventListener("touchstart", onTouchStart, false);
+    scope.domElement.addEventListener("wheel", onMouseWheel, { passive: false });
+    scope.domElement.addEventListener("touchstart", onTouchStart, { passive: false });
     scope.domElement.addEventListener("touchend", onTouchEnd, false);
-    scope.domElement.addEventListener("touchmove", onTouchMove, false);
+    scope.domElement.addEventListener("touchmove", onTouchMove, { passive: false });
     window.addEventListener("keydown", onKeyDown, false);
 
     this.update(); // force an update at start