Sliding panels release

- [ ] Documentation/demos update
- [x] Fix styling for fragment links view
- [x] Improve styling for collapsed page label
- [ ] post in manifold markets link/create a market abot it?
- [x] figure out a better keyboard shortcut, as the current one does not quite work reliably =\
  - though actually this one may be about link initiation not covering dynamically appearing links!
    - yep!