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.

internal/platform/ops_other.go

@@ -2,7 +2,10 @@
 
 package platform
 
-import "errors"
+import (
+	"errors"
+	"os"
+)
 
 // TrashName is the user-facing name of the trash.
 const TrashName = "trash"
@@ -12,3 +15,10 @@ func Reveal(string) error { return errors.New("not supported on this platform")
 
 // Trash is unsupported on this platform.
 func Trash(string, Expect) error { return errors.New("trash not supported on this platform") }
+
+// Headless reports whether there is no graphical session (no X or Wayland
+// display), so there is no file manager to open and no desktop trash anyone
+// will empty.
+func Headless() bool {
+	return os.Getenv("DISPLAY") == "" && os.Getenv("WAYLAND_DISPLAY") == ""
+}