Several improvements to tldraw whiteboard:
- Only send the shape diff on shape updates (reduce a lot the message traffic)
- Shape permissions (don't allow others to select/edit unless you are presenter/moderator)
- This required some changes in akka model
- Tldraw state patch changes to improve stability with fast updates (fix several crashes)
Fixes a case when the presentation is just uploaded and a wrong initial zoom was set.
Also fix viewer zoom not correclty adjusting to the area size when zoomed out.
- Poll result as text shape in the lower right-hand
- Include all tldraw shape bounds as size in akka (to help Daniel rendering in pdf export)
- Default/initital zoom will be centered in the slide and maximize the size according to the presentation area
- Also limited the max zoom out to be the one that fits the slide, to be similar as we had before
