[ingvarch]

What changes

Three things for reading and keeping long texts: logs, files, descriptions and
plans.

• With wrap off, left/h and right/l move a text sideways by a quarter
  of the window, up to where the end of the widest line meets the right edge.
  Logs and files say how far on the toggles line (Column:41), other text
  screens in the title. home goes back to the start of the lines first, then
  to the top; g always goes to the top. Wrap on puts the text back at the
  start. Find and filter matches move with the text. On a plan, left and right
  still choose a button.
• ctrl+s asks for the path on the line at the top, with the name it used to
  save under already typed, so enter keeps it. ~/ is the home folder, a
  relative path is from where urga runs, missing folders are made, and an
  existing file is overwritten only after a question. The status line says
  where it was saved.
• e on the log of a task reads the 1 MiB before what is shown, across the
  rotated files that are still there, and puts it above the lines already on
  the screen without moving the window. The title then says how much of the
  log is read, as a file's does. The line limit of Followed logs grow without a limit and slow the UI down #63 still holds. It needs a
  token that can read the files of the allocation; without it the status line
  shows the refusal.

Found and fixed along the way: a tab in a description is drawn as four spaces,
so a line with a tab now moves sideways by the same cells it is drawn in.
Nomad writes log paths with backslashes on a Windows client; reading further
back takes that into account.

A test that ends while it leaves the session write running failed on the
Windows runner, where that write is slow: the write landed in the test's
folder while it was being removed. The tests that load a session config now
write it once more when they end, which waits for a write still running and
leaves nothing for a later one to write (its own commit, chore(ui)).

Left for later (in the ideas list): f and n do not move the text sideways
to a match past the right edge; after the stream drops lines off the front,
the title keeps the size read by the last e.

Closes #107
Closes #108
Closes #106

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): ...