feat(tui): show a result's file name and folder in columns of their own

The results list held the whole shared path in one column, so a search
was read through its folder: every row began with the same peer prefix
and the file name, the part being searched for, sat off the right edge.
Split the column at the last separator, the file name first with the
larger share of the width and the folder dimmed beside it, so names line
up and read at a glance.

The one scroll offset moves both columns together, and $ runs to the end
of whichever overflows further. The website's mock of the pane follows.

Suggested in #55.

README.md

@@ -92,13 +92,13 @@ Everything else is a one-shot command that runs headless.
 
 ### The TUI
 
-Results run across the top, with the whole width for long file names;
-Searches, Downloads and Info share the row underneath. `Tab`/`Shift-Tab` or
-`1`–`3` move the focus between panes, `z` zooms the focused pane to the whole
-window, and `w` hides it so the others widen (its number brings it back).
-Every list takes `↑`/`↓`, `Home`/`End`, `PgUp`/`PgDn` and the vim keys, and
-`h`/`l` or `←`/`→` scroll a long file name or query sideways, `0` and `$` to
-either end. `PgUp`/`PgDn` scroll a chat log back through its history, and `?`
+Results run across the top, each file name in a column of its own with the
+folder it came from beside it; Searches, Downloads and Info share the row
+underneath. `Tab`/`Shift-Tab` or `1`–`3` move the focus between panes, `z`
+zooms the focused pane to the whole window, and `w` hides it so the others
+widen (its number brings it back). Every list takes `↑`/`↓`, `Home`/`End`,
+`PgUp`/`PgDn` and the vim keys, and `h`/`l` or `←`/`→` scroll a long file name,
+folder or query sideways, `0` and `$` to either end. `PgUp`/`PgDn` scroll a chat log back through its history, and `?`
 shows every key for where you are.
 
 ### Daemon mode