feat: Wizard shortcut on the desktop and in the launcher

- Menu item: desktop icon + launcher entry that run the newest release in Konsole.
- Icon: Valve's return icon with a gear (assets/steam-gaming-settings.svg), published with each release.
- Desktop files are written already executable, so Plasma runs them.
- VERSION 0.9.0.

lib/wizard-shortcut.sh

@@ -0,0 +1,80 @@
+#!/bin/bash
+# "Wizard shortcut" menu item: a desktop icon and an app launcher entry that
+# open the newest release of this wizard in Konsole (curl | bash, like the
+# install command in the README), so it's never out of date.
+# Sourced by setup-gamescope-boot.sh; not meant to be run on its own.
+
+WIZARD_RELEASE="https://github.com/theupriser/cachyos-gamescope-boot/releases/latest/download"
+WIZARD_URL="$WIZARD_RELEASE/setup-gamescope-boot.sh"
+# Steam logo with a gear (assets/ in the repo, published with every release).
+WIZARD_ICON="${XDG_DATA_HOME:-$HOME/.local/share}/icons/hicolor/scalable/apps/cachyos-gamescope-boot-wizard.svg"
+WIZARD_LAUNCHER="${XDG_DATA_HOME:-$HOME/.local/share}/cachyos-gamescope-boot/run-wizard"
+WIZARD_DESKTOP_NAME="cachyos-gamescope-boot-wizard.desktop"
+WIZARD_APP_ENTRY="${XDG_DATA_HOME:-$HOME/.local/share}/applications/$WIZARD_DESKTOP_NAME"
+
+wizard_desktop_file() {
+    echo "$(xdg-user-dir DESKTOP 2>/dev/null || echo "$HOME/Desktop")/$WIZARD_DESKTOP_NAME"
+}
+
+install_executable() {
+    # install_executable <dest> <mode>: stdin to <dest>, with its mode set
+    # before it appears. Plasma treats a desktop icon it saw while it wasn't
+    # executable yet as untrusted and opens it in an editor.
+    local dest="$1" tmp
+    mkdir -p "$(dirname "$dest")"
+    tmp="$(mktemp "$(dirname "$dest")/.tmp.XXXXXX")"
+    cat > "$tmp"
+    chmod "$2" "$tmp"
+    mv -f "$tmp" "$dest"
+}
+
+launcher_status() {
+    [[ -x "$WIZARD_LAUNCHER" && -f "$WIZARD_APP_ENTRY" ]]
+}
+
+launcher_enable() {
+    info "Adding the wizard shortcut (desktop icon and app launcher entry)..."
+    install_executable "$WIZARD_LAUNCHER" 755 << EOF
+#!/bin/bash
+# Installed by cachyos-gamescope-boot: run the newest release of the wizard.
+if ! curl -fsSL --max-time 30 "$WIZARD_URL" | bash; then
+    echo
+    echo "Couldn't download or run the wizard. Are you connected to the internet?"
+fi
+echo
+read -rp "Press Enter to close this window... " _
+EOF
+
+    # The icon comes with the release; without it, Steam's own icon.
+    local icon=steam tmp
+    tmp="$(mktemp)"
+    if curl -fsSL --max-time 20 "$WIZARD_RELEASE/steam-gaming-settings.svg" -o "$tmp" && grep -q '<svg' "$tmp"; then
+        install -D -m 644 "$tmp" "$WIZARD_ICON"
+        icon=cachyos-gamescope-boot-wizard
+        gtk-update-icon-cache -q -f -t "${XDG_DATA_HOME:-$HOME/.local/share}/icons/hicolor" 2>/dev/null || true
+    else
+        warn "Couldn't download the shortcut's icon; using Steam's icon instead."
+    fi
+    rm -f "$tmp"
+
+    local entry
+    entry="[Desktop Entry]
+Type=Application
+Name=SteamOS Setup Wizard
+Comment=Turn the SteamOS-style parts of this PC on or off (cachyos-gamescope-boot)
+Exec=konsole -e $WIZARD_LAUNCHER
+Icon=$icon
+Terminal=false
+Categories=System;Settings;"
+    printf '%s\n' "$entry" | install_executable "$WIZARD_APP_ENTRY" 644
+    printf '%s\n' "$entry" | install_executable "$(wizard_desktop_file)" 755
+    kbuildsycoca6 >/dev/null 2>&1 || true
+    ok "Wizard shortcut added: \"SteamOS Setup Wizard\" on the desktop and in the launcher."
+}
+
+launcher_disable() {
+    rm -f "$(wizard_desktop_file)" "$WIZARD_APP_ENTRY" "$WIZARD_LAUNCHER" "$WIZARD_ICON"
+    rmdir "$(dirname "$WIZARD_LAUNCHER")" 2>/dev/null || true
+    kbuildsycoca6 >/dev/null 2>&1 || true
+    ok "Wizard shortcut removed."
+}