Initialize project and update portal port configuration

Set default portal port to 8081, fix Dart build issue in cart screen, and update setup documentation.

Co-Authored-By: Oz <oz-agent@warp.dev>

install_portal.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -Eeuo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_DIR="$SCRIPT_DIR"
+COMPOSE_FILE="$PROJECT_DIR/docker-compose.yml"
+ENV_FILE="$PROJECT_DIR/.env"
+
+if [[ ! -f "$COMPOSE_FILE" ]]; then
+  echo "docker-compose.yml not found in $PROJECT_DIR"
+  exit 1
+fi
+
+if [[ ! -f "$ENV_FILE" ]]; then
+  cp "$PROJECT_DIR/.env.example" "$ENV_FILE"
+  echo "Created $ENV_FILE from .env.example"
+  echo "Update Firebase variables in .env before first production login test."
+fi
+
+docker compose -f "$COMPOSE_FILE" --env-file "$ENV_FILE" up -d --build
+
+PORT="$(grep '^PORTAL_PORT=' "$ENV_FILE" | cut -d= -f2 || true)"
+PORT="${PORT:-8081}"
+
+echo
+echo "Portal is running at: http://localhost:${PORT}"