Add support for fast eink + marker access

[declan-wtg]

Adds a InkCanvas component, built off of QQuickPaintedItem, to support the fast small refresh writing, like xochitl uses for its notes. Links against libQt6Quick for QQuickPaintedItem.

This code is entirely AI generated, but has been tested and I've taken a quick look through it. Looks to be serviceable.

Note: has only been tested on the reMarkable Paper Pro, as that's the only one I got lol.

[declan-wtg]

Because of AppLoad/xochitl limitations, you can't get access to the raw evdev device that you need to directly handle marker events, so it's based off the mouse events you get instead.

This makes it pretty... bad:

• Palm rejection works, but having your palm on it can mess up the detection
• There can be some issues where it doesn't detect you've started writing until a little bit into the stroke, but it catches up alright and from there it's pretty smooth sailing.

Am working on erasers, but I think that's application side for now, since this already has eraseAt(...).

[declan-wtg]

Just added support for marker, exposed through net.asivery.Marker.

This basically fixes all the issues with palm rejection and whatnot. I think the lag is still there, but it's better now, and I think the rest is just my test app.

Access to when we're erasing (using the other side of the pencil) works too.