Rename refresh-bar -> refresh-shell, restart-quickshell -> restart-shell

The bin names should reflect the thing they manage. `refresh bar` is
misleading because the command resets the entire shell.json (which holds
plugins beyond just the bar), and `restart quickshell` names the runtime
rather than the product. Both now end in `-shell` to match the rest of
omarchy-shell.

Updates every caller in autostart, the menu, voxtype helpers, and the
shell README. No behavior changes.

bin/omarchy-refresh-shell

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# omarchy:summary=Reset shell.json to Omarchy defaults
+# omarchy:examples=omarchy refresh shell
+
+set -e
+
+USER_CONFIG="$HOME/.config/omarchy/shell.json"
+
+# Removing the user file lets the running shell fall back to shell-defaults.json
+# via its FileView watcher. The next shell start will also use the defaults.
+if [[ -f $USER_CONFIG ]]; then
+  backup="$USER_CONFIG.bak.$(date +%s)"
+  cp "$USER_CONFIG" "$backup"
+  echo "Backed up user shell config to $backup"
+  rm -f "$USER_CONFIG"
+fi