Add movie mode for watching videos on the external monitor

The screen layout and trayer setup moved from xmonad.hs to a shared
screen-layout script. lf opens videos with movie.

.local/bin/movie

@@ -0,0 +1,14 @@
+#!/bin/bash
+# Plays videos on the external monitor only, with the laptop screen off.
+# Opened from lf for video/* files; restores the normal layout when mpv exits.
+
+# Single-screen mode only makes sense with the external monitor plugged in
+if ! xrandr --query | grep -q '^HDMI-1-0 connected'; then
+    exec mpv "$@"
+fi
+
+trap ~/.local/bin/screen-layout EXIT
+trap 'exit 130' INT TERM HUP
+
+xrandr --output eDP-1 --off
+mpv "$@"

.local/bin/screen-layout

@@ -0,0 +1,21 @@
+#!/bin/bash
+# Sets up the outputs, wallpaper and trayer for whatever monitors are connected.
+# Called by xmonad at startup and on monitor (dis)connect, and by `movie` on exit.
+
+if xrandr --query | grep -q '^HDMI-1-0 connected'; then
+    xrandr --output HDMI-1-0 --preferred --primary --output eDP-1 --right-of HDMI-1-0 --preferred
+    tray=1
+else
+    xrandr --output eDP-1 --preferred --primary --output HDMI-1-0 --off
+    tray=0
+fi
+
+~/.fehbg
+
+# Replace any running trayer, so there's never more than one
+pkill -x trayer
+while pgrep -x trayer > /dev/null; do sleep 0.1; done
+trayer -l --edge top --align right --SetDockType true \
+    --SetPartialStrut true --expand true --widthtype request \
+    --tint 0x232634 --height 18 --monitor "$tray" > /dev/null 2>&1 &
+disown