fix: replace xprop with x11-utils, use apt websocket-client package

xprop is not a Debian package name — it's in x11-utils. Also replace
pip3 install with python3-websocket from apt (same library, no pip needed).
This fixes the apt failure that prevented lightdm from being installed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

install-kiosk.sh

@@ -39,20 +39,17 @@ apt-get install -y \
   openbox \
   lightdm \
   xserver-xorg \
+  x11-utils \
   xdotool \
-  xprop \
   python3 \
   python3-pyqt5 \
-  python3-pip \
+  python3-websocket \
   sqlite3 \
   git \
   curl \
   openssh-server \
   2>&1 | grep -Ev "^(Reading|Selecting|Preparing|Unpacking|Setting|Processing|Triggers|Get)"
 
-echo "==> Installing websocket-client..."
-pip3 install --break-system-packages websocket-client 2>&1 | tail -2
-
 # ── Kiosk repo ─────────────────────────────────────────────────────
 echo "==> Cloning kiosk repo..."
 if [ ! -d "$REPO_DIR" ]; then