TwistyAlgEditorV2: keep the timestamp at opposite-anchor

[lgarron]

To Reproduce
Steps to reproduce the behavior:

1. Go to http://localhost:3333/alpha.twizzle.net/edit/?alg=R+U+R%27

The cursor jumps to 250ms, because <twisty-alg-editor-v2> is telling it that the cursor is at the beginning.

Expected behavior

The cursor should stay at the end of the alg.

This is not a huge deal, since alg.cubing.net doesn't even do this well. And I also felt comfortable merging to main with this bug in place. But I'd like to fix it as soon as possible.

This is probably not a good bug for someone else to tackle, since the current TwistyAlgEditorV2 code is not great:

cubing.js/src/cubing/twisty/views/TwistyAlgEditor/TwistyAlgEditorV2.ts

Lines 1 to 12 in 8bfc286

	/**
	* Warning: the current implementation of <twisty-alg-editor-v2> is *not good*,
	* but it is *good enough*. The important parts is that:
	*
	* - The editor can be used in apps without much effort.
	* - The editor handles alg validation and move highlighting *okay* when not
	* connected to a `<twisty-player-v2>`.
	* - The editor stays in sync if it's connected to a `<twisty-player-v2>`.
	*
	* The current implementation still has some race conditions and edge cases. A
	* proper rewrite with a better model would be very welcom.
	*/