fix(home): keep waybar + wallpaper on surviving monitor after unplug

Hyprland drops the layer-shell surfaces on the remaining output when a
monitor is removed and does not recreate them, so waybar and the awww
wallpaper vanish on unplug. The socket2 watcher only reacted to
`monitoradded`, which masked it — reconnecting re-fired the add and
restored both. Handle `monitorremoved` too, and on either event re-push
the wallpaper and reload waybar (SIGUSR2 rebuilds its per-output bars).
Renamed `wallpaper-hotplug` to `monitor-hotplug` since it now does both.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/media.nix

@@ -21,15 +21,21 @@ let
   # awww-daemon paints only the outputs present when `awww img` last ran and does
   # not repaint a monitor hotplugged afterwards — it comes up on the fill color
   # (black), and a transparent foot on it then shows that black, not the
-  # wallpaper. Watch Hyprland's event socket and re-push the wallpaper (setbg
-  # with no arg → all current outputs) on each monitor-add. Hyprland emits both
-  # `monitoradded` and `monitoraddedv2`; match only the former so setbg fires
-  # once. Runs as a Hyprland exec-once (see home.nix).
-  wallpaperHotplug = pkgs.writeShellScriptBin "wallpaper-hotplug" ''
+  # wallpaper. Symmetric problem on unplug: removing an output makes Hyprland
+  # drop and not recreate the layer-shell surfaces on the surviving monitor, so
+  # its waybar and wallpaper vanish. Watch Hyprland's event socket and, on either
+  # add or remove, re-push the wallpaper (setbg with no arg → all current
+  # outputs) and reload waybar (SIGUSR2 rebuilds its per-output bars). Hyprland
+  # emits both `monitoradded` and `monitoraddedv2`; match only the non-v2 forms
+  # so each side fires once. Runs as a Hyprland exec-once (see home.nix).
+  monitorHotplug = pkgs.writeShellScriptBin "monitor-hotplug" ''
     sock="''${XDG_RUNTIME_DIR}/hypr/''${HYPRLAND_INSTANCE_SIGNATURE}/.socket2.sock"
     ${pkgs.socat}/bin/socat -u UNIX-CONNECT:"$sock" - | while IFS= read -r line; do
       case "$line" in
-        "monitoradded>>"*) setbg ;;
+        "monitoradded>>"* | "monitorremoved>>"*)
+          setbg
+          ${pkgs.procps}/bin/pkill -USR2 -x .waybar-wrapped || true
+          ;;
       esac
     done
   '';
@@ -66,7 +72,7 @@ in
 
   home.packages = with pkgs; [
     setbg
-    wallpaperHotplug # re-push wallpaper to a hotplugged monitor (see comment above)
+    monitorHotplug  # re-push wallpaper + reload waybar on monitor add/remove (see comment above)
     awww            # wayland wallpaper daemon (setbg backend)
     wl-clipboard    # wl-copy, for the yank binds
     imagemagick     # `magick`: rotate/flip binds