feat: add basic touchscreen support

This is basically a migration from mouse events to
[pointer events](
  https://developer.mozilla.org/en-US/docs/Web/API/Pointer_events
).

The `PointerEvent` interface inherits all of the `MouseEvent`
properties, meaning that existing code can essentially be left
as-is. The only major change is making sure we only respond to the
"primary" pointer.

Known issues include:
* stylus hover is not detected
* touchscreens do not have a concept of hover, making it difficult
  to e.g. resize areas
* no touch gesture support, e.g. "pinch-to-zoom"

src/components/EditorHeader/ControlPanel.jsx

@@ -1526,8 +1526,8 @@ export default function ControlPanel({
               )}
               <div
                 className="text-xl  me-1"
-                onMouseEnter={() => setShowEditName(true)}
-                onMouseLeave={() => setShowEditName(false)}
+                onPointerEnter={(e) => e.isPrimary && setShowEditName(true)}
+                onPointerLeave={(e) => e.isPrimary && setShowEditName(false)}
                 onClick={() => setModal(MODAL.RENAME)}
               >
                 {window.name.split(" ")[0] === "t" ? "Templates/" : "Diagrams/"}