feat: support running using Docker Compose

This commit adds a Docker Compose file which will run the application
using docker. The application is fronted by Traefik, and runs using
PHP-fpm. nginx is used to accept queries from Traefik and relay them to
the PHP-fpm containers (Traefik doesn't support FastCGI directly).
Sessions are shared between the various PHP containers using memcached.

Part of this work is based on [this repo](https://github.com/wandersonwhcr/docker-nginx-php-fpm)

docker/Dockerfile

@@ -0,0 +1,37 @@
+# syntax=docker/dockerfile:1.7-labs
+ARG PHP_VERSION=8.3
+ARG POSTGRESQL_VERSION=17
+
+#
+# Application image
+#
+
+FROM php:${PHP_VERSION}-fpm-alpine AS application
+
+RUN <<EOF
+	set -e
+	apk add --no-cache fcgi unzip postgresql-dev libmemcached-dev \
+		libmemcached autoconf pkgconfig g++ zlib-dev make
+	docker-php-ext-install pgsql pdo pdo_pgsql
+	pecl install memcached
+	docker-php-ext-enable memcached
+	mkdir -p /var/www/tasks
+	echo "pm.status_path = /status" >> /usr/local/etc/php-fpm.d/zz-docker.conf
+	echo "chdir = /var/www/tasks/site" >> /usr/local/etc/php-fpm.d/zz-docker.conf
+	curl --silent --remote-name https://raw.githubusercontent.com/renatomefi/php-fpm-healthcheck/v0.5.0/php-fpm-healthcheck
+	install --owner root --group root --mode 755 php-fpm-healthcheck /usr/local/bin/php-fpm-healthcheck
+	rm -rf php-fpm-healthcheck
+	mv "$PHP_INI_DIR/php.ini-production" "$PHP_INI_DIR/php.ini"
+EOF
+HEALTHCHECK --interval=5s \
+    CMD php-fpm-healthcheck || exit 1
+
+COPY --parents site includes arse /var/www/tasks/
+
+#
+# Database image
+#
+
+FROM postgres:${POSTGRESQL_VERSION} AS database
+RUN mkdir /opt/tasks
+COPY --parents database.sql database /opt/tasks/