[ingvarch]

What changes

The tests no longer read what a command is still writing. playOut, which runs what a key started the way the program does, told a command that waits on a stream from slow work by time: one that had not answered 100 ms after it started was left running. On a slow runner under the race detector the fake editor took longer, playOut returned, and TestDispatch_WithAPriority read the editor while the command still wrote it (a data race in CI on #179).

• A command waits on a stream only through waitOn (internal/ui/stream.go), used by the event feed, the log lines and the watch of changes. In the program it waits as before. While playOut runs, a wait answers at once with what has come, or with nothing, the way held timers already do.
• Every other command is run until it answers. One that takes more than 5 s panics with the name of the command, instead of hanging the run.
• A guard test keeps every blocking channel receive in internal/ui inside waitOn, like the guard on timers. AGENTS.md rule 3 says so.
• Nothing waits on time any more, so internal/ui runs faster: about 30 s to 10 s without the race detector.

Production behaviour does not change.

Closes #182

Checklist

• The test for this change was written first and failed
• make check is green
• The title is a conventional commit: feat(ui): ..., fix(nomad): ...