mapsize 1.2.0: permanent delete and in-map reveal when headless

On a headless Linux or BSD system (no DISPLAY or WAYLAND_DISPLAY) nothing
empties the freedesktop trash, so trashing never freed space. There, d now
deletes permanently after an explicit confirmation, checking owner and type
against the scan and removing through an os.Root on the parent so a swapped
symlink cannot redirect it. o shows the folder in the map instead of
launching a file manager. Desktop sessions, macOS and Windows are unchanged.

docs/mapsize.1

@@ -1,5 +1,5 @@
 .\" Manual page for mapsize. View with: man -l docs/mapsize.1
-.TH MAPSIZE 1 "October 2026" "mapsize 1.1.0" "User Commands"
+.TH MAPSIZE 1 "October 2026" "mapsize 1.2.0" "User Commands"
 .SH NAME
 mapsize \- interactive terminal disk usage analyser with a navigable treemap
 .SH SYNOPSIS
@@ -95,7 +95,7 @@ Useful over SSH, where \fBCOLORTERM\fR is often not forwarded.
 Disable mouse support. Everything works from the keyboard.
 .TP
 .B \-\-read\-only
-Disable every action that modifies the filesystem (moving to trash) and
+Disable every action that modifies the filesystem (trash and delete) and
 show \fBREAD ONLY\fR in the header. Saving a snapshot file is still
 allowed. This does not make
 .B mapsize
@@ -223,10 +223,14 @@ Toggle allocated / logical size.
 Copy the selected path to the clipboard (OSC 52; terminal support varies).
 .TP
 .B o
-Reveal the selected item in the desktop file manager.
+Reveal the selected item in the desktop file manager. On a headless system
+(no \fBDISPLAY\fR or \fBWAYLAND_DISPLAY\fR), show the folder in the map
+instead.
 .TP
 .BR d ", " Delete
-Move the selected item to the trash after confirmation. Disabled with
+Move the selected item to the trash after confirmation. On a headless
+Linux or BSD system, where nothing would empty the trash, delete it
+permanently instead after a confirmation that says so. Disabled with
 \fB\-\-read\-only\fR, for snapshots, and while scanning.
 .TP
 .B s