hyprland: add SUPER+arrow workspace cycling and overview binds

SUPER+Left/Right cycle existing workspaces on the active monitor
(m+1/m-1 with cycling enabled), SUPER+Up opens the hyprshell overview
scoped to the current monitor (create/manage workspaces there), and
SUPER+Down closes the overview again. Adds binds-help.sh cheat sheet
(SHIFT+SUPER+H) and overview-close.sh helper.

hyprland/.local/bin/overview-close.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# macOS-style SUPER+Down: close the hyprshell workspace overview if it is open,
+# returning to the current workspace without switching.
+#
+# hyprshell's overview is a gtk4-layer-shell surface whose namespace is
+# "hyprshell_overview", and the OpenOverview IPC message toggles the overview
+# closed when it is already open (see OverviewRootInput::OpenOverview).
+set -u
+
+if ! hyprctl layers -j | jq -e '
+    .. | objects | .namespace? // empty | select(. == "hyprshell_overview")
+' >/dev/null; then
+    exit 0
+fi
+
+hyprshell socat '"OpenOverview"'