New documentation panel

[kazcw]

### Tasks
- [x] Yjs: Panel <-> AST sync (Y.Text)
- [x] First parser: Header
- [x] First decorator: Link
- [x] Image decorator (with project image URL support)
- [ ] Remaining parsers: Bulleted list, numbered list, blockquote
- [ ] CSS for all markdown syntax
- [ ] --- PR replacing Lexical doc editor ---
- [ ] Yjs: Code editor <-> AST sync
- [ ] Accurate content size: Render images offscreen to compute sizes, use a StateEffect to "replace" decorations to update estimates
- [ ] Toolbars
- [x] Fix panel slide-in animation

[enso-bot[bot]]

Keziah Wesley reports a new STANDUP for yesterday (2024-10-03):

Progress: Working on image support: Implemented teleportation, computed-facet based plugin. Noticed right-dock slide-in animation has been broken, fixed it. It should be finished by 2024-10-11.

Next Day: Next day I will be working on the #11240 task. Finish image support.

[enso-bot[bot]]

Keziah Wesley reports a new STANDUP for today (2024-10-04):

Progress: Finishing images: Got the teleportation mechanism working with CM's decoration-reuse model. It should be finished by 2024-10-11.

Next Day: Next day I will be working on the #11240 task. Modified parsers for remaining space-mishandling syntaxes.