feat: add standalone (frontend-only) mode via VITE_STANDALONE build flag

- App.tsx: bypass auth gate, swap canvas save/load to localStorage
- Sidebar.tsx: hide scan views and Scan Network button
- useStatusPolling.ts: skip WebSocket connection
- Dockerfile.frontend: accept VITE_STANDALONE build arg
- docker-publish.yml: build ghcr.io/pouzor/homelable-frontend-standalone image
- docker-compose.standalone.yml: frontend-only compose file
- install.sh: add --standalone flag

Usage:
  curl -fsSL .../install.sh | bash -s -- --standalone
  cd homelable && docker compose up -d

install.sh

@@ -4,39 +4,61 @@ set -euo pipefail
 REPO="Pouzor/homelable"
 INSTALL_DIR="${HOMELABLE_DIR:-homelable}"
 RAW="https://raw.githubusercontent.com/${REPO}/main"
+STANDALONE=0
+
+for arg in "$@"; do
+  case $arg in
+    --standalone) STANDALONE=1 ;;
+  esac
+done
 
 # Detect install vs update
 if [ -f "${INSTALL_DIR}/docker-compose.yml" ]; then
   echo "Updating Homelable in ./${INSTALL_DIR}/"
   IS_UPDATE=1
 else
-  echo "Installing Homelable into ./${INSTALL_DIR}/"
+  if [ "${STANDALONE}" -eq 1 ]; then
+    echo "Installing Homelable (standalone mode) into ./${INSTALL_DIR}/"
+  else
+    echo "Installing Homelable into ./${INSTALL_DIR}/"
+  fi
   IS_UPDATE=0
 fi
 
 mkdir -p "${INSTALL_DIR}"
 cd "${INSTALL_DIR}"
 
-# Always update docker-compose.yml and refresh .env.example
-curl -fsSL "${RAW}/docker-compose.prebuilt.yml" -o docker-compose.yml
-curl -fsSL "${RAW}/.env.example" -o .env.example
+if [ "${STANDALONE}" -eq 1 ]; then
+  curl -fsSL "${RAW}/docker-compose.standalone.yml" -o docker-compose.yml
+else
+  curl -fsSL "${RAW}/docker-compose.prebuilt.yml" -o docker-compose.yml
+  curl -fsSL "${RAW}/.env.example" -o .env.example
+fi
 
 if [ "${IS_UPDATE}" -eq 1 ]; then
   echo ""
   echo "  docker-compose.yml updated."
-  echo "  Check .env.example for any new variables, then restart:"
+  echo "  Restart with:"
   echo "    cd ${INSTALL_DIR} && docker compose pull && docker compose up -d"
 else
-  if [ ! -f .env ]; then
-    cp .env.example .env
+  if [ "${STANDALONE}" -eq 1 ]; then
+    echo ""
+    echo "  Standalone mode: no backend, no login, canvas saves to browser localStorage."
+    echo ""
+    echo "  Run:"
+    echo "    cd ${INSTALL_DIR} && docker compose up -d"
+  else
+    if [ ! -f .env ]; then
+      cp .env.example .env
+    fi
+    echo ""
+    echo "  Edit .env if needed (default login: admin / admin):"
+    echo "    - Set SECRET_KEY to a random string"
+    echo "    - Change AUTH_PASSWORD_HASH before exposing on a network"
+    echo ""
+    echo "  Run:"
+    echo "    cd ${INSTALL_DIR} && docker compose up -d"
   fi
   echo ""
-  echo "  Edit .env if needed (default login: admin / admin):"
-  echo "    - Set SECRET_KEY to a random string"
-  echo "    - Change AUTH_PASSWORD_HASH before exposing on a network"
-  echo ""
-  echo "  Then run:"
-  echo "    cd ${INSTALL_DIR} && docker compose up -d"
-  echo ""
   echo "  Open http://localhost:3000"
 fi