Polish the board server App view

[dglazkov]

Most of the App view has already landed, but let's track the remaining issues:

• [x] Teach App view to stop/restart gracefully
• [x] Teach App view to handle invite links
• [x] Teach App view to handle multimodal content
• [ ] Teach App view to group "uneventful" events
• [x] Teach App view to handle errors like this one

[dglazkov]

re: grouping -- WDYT about inventing a new log entry type: a group of nodes. Then, our rendering is simple: just show the group. We can ask to expand the group, and it contains nodes that had no interesting edges.

[paullewis]

+1

I feel like we could start a new group whenever we get an edge with an input/output in it, or when we get an empty edge after one with an input/output in it. Like so:

[group]
  edge (input)
[/group]
[group]
  edge (empty)
  edge (empty)
  edge (empty)
[/group]
[group]
  edge (output)
[/group]
[group]
  edge (input)
[/group]
[group]
  edge (empty)
[/group]
[group]
  edge (output)
[/group]

Then from a UI perspective any group with just one entry in it doesn't have any expand/collapse functionality because it's not relevant, but what this gives us is a consistent "everything is part of a group" structure, rather than "some things are grouped, others are not".

wdyt?