feat: add one-liner install script

curl -fsSL https://raw.githubusercontent.com/Pouzor/homelable/main/install.sh | bash

Handles fresh install and updates. Pulls prebuilt images, creates .env from
.env.example on first run. Update README Quick Start accordingly.

install.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+REPO="Pouzor/homelable"
+INSTALL_DIR="${HOMELABLE_DIR:-homelable}"
+RAW="https://raw.githubusercontent.com/${REPO}/main"
+
+# 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 ./${INSTALL_DIR}/"
+  IS_UPDATE=0
+fi
+
+mkdir -p "${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 "${RAW}/.env.example" -o .env.example
+
+if [ "${IS_UPDATE}" -eq 1 ]; then
+  echo ""
+  echo "  docker-compose.yml updated."
+  echo "  Check .env.example for any new variables, then restart:"
+  echo "    cd ${INSTALL_DIR} && docker compose pull && 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 "  Then run:"
+  echo "    cd ${INSTALL_DIR} && docker compose up -d"
+  echo ""
+  echo "  Open http://localhost:3000"
+fi