feat(tui): W puts the pane layout back

Hiding panes with w and zooming with z had no way back short of
pressing each hidden pane's number and Esc. W shows every pane and
leaves zoom in one go, and the shortcut bar offers it only while there
is a layout to reset.

README.md

@@ -95,11 +95,12 @@ Everything else is a one-shot command that runs headless.
 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 `$` to either end. `PgUp`/`PgDn` scroll a
-chat log back through its history, and `?` shows every key for where you are.
+zooms the focused pane to the whole window, `w` hides it so the others widen
+(its number brings it back), and `W` puts the whole layout back. Every list
+takes `↑`/`↓`, `Home`/`End`, `PgUp`/`PgDn` and the vim keys, and `h`/`l` or
+`←`/`→` scroll a long file name, folder or query sideways, `0` and `$` to
+either end. `PgUp`/`PgDn` scroll a chat log back through its history, and `?`
+shows every key for where you are.
 
 ### Daemon mode