Node groups, saliency, smart variables, making the demo scene look better

Added support for node groups, saliency strategies (defaults to RandomBestLeastRecentlyViewed), smart variables, plus other improvements under the hood.
Made the demo scene look a lil nicer / fixed some timing bugs.

Playdate.2025-07-06_03-50-29.mp4

Action Markup Handlers! Blips and Pauses!

Added early support for action markup handlers. These are used to react to line content as is being presented.
Examples now in the demo are a handler for the [pause /] markup and a handler that plays blips as text is displayed.

Playdate.2025-07-02_00-57-30.mp4

Dialogue presenters! Typewriter!

• Text now renders in something close to a textbox
• Have some dialogue presenter infrastructure set up (demo uses two that interact via cancelation token to implement hurry-up / continue)
• Early typewriter functionality!
• Not outwardly visible, but doing a bunch of cleanup / namespace-ing now that I'm getting more of a feel for playdate/lua conventions (tbd on if that feel is correct lol)

More progress (markup parsing!)

Update to the initial demo! Markup parsing works now! Still some bugs, and don't have the built in markup processors yet, but registering replacement marker processors works! (have example for [bold] and [italic]). Also the line handler doesn't really use attributes yet, but they are getting extracted (including the implicit character attribute).

Initial wip demo

This is the initial demo! Most things still don't work but it's a not a bad start for a couple weekends