feat: docker compose dev environment

Replaces the bare-metal `composer run dev` workflow with a fully
containerized 9-service stack orchestrated by docker compose. Single
command brings up the full app — three subdomains (marketing /
account / admin) reachable via Traefik with TLS, MariaDB + Valkey
+ Mailpit + Vite HMR + Horizon + scheduler all wired in.

Components:
- docker-compose.yml: traefik, app (php-fpm), web (nginx), mariadb,
  valkey, mailpit, vite, horizon, scheduler.
- docker/: Dockerfiles, nginx config, entrypoint scripts.
- Makefile: convenience targets (up / down / logs / shell / migrate
  / seed / test / pint / etc).
- .env.docker.example: template for Docker-stack environment vars
  (separate from website/.env so bare-metal devs aren't disrupted).
- website/vite.config.ts: server.host / origin / hmr / cors hooks
  driven by VITE_HOST / VITE_ORIGIN / VITE_HMR_HOST so the same
  config serves both bare-metal and Docker.
- website/bootstrap/app.php: redirectGuestsTo() now uses
  request()->getScheme() so http: dev hosts don't get force-https
  redirects.
- composer.json: drops laravel/sail (replaced by this stack).
- docs/superpowers/specs/2026-04-25-docker-compose-dev-environment-design.md:
  full design spec.

Bare-metal `composer run dev` workflow stays usable for anyone who
prefers it — Docker stack reads .env.docker, doesn't fight
website/.env.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker/app/Dockerfile

@@ -0,0 +1,64 @@
+FROM php:8.3-fpm-bookworm
+
+ARG UID=1000
+ARG GID=1000
+
+ENV COMPOSER_ALLOW_SUPERUSER=1 \
+    COMPOSER_NO_INTERACTION=1 \
+    COMPOSER_MEMORY_LIMIT=-1
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+        git \
+        unzip \
+        curl \
+        ca-certificates \
+        libzip-dev \
+        libpng-dev \
+        libjpeg-dev \
+        libfreetype6-dev \
+        libwebp-dev \
+        libicu-dev \
+        libonig-dev \
+        libxml2-dev \
+        libcurl4-openssl-dev \
+        libssl-dev \
+        pkg-config \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN docker-php-ext-configure gd --with-freetype --with-jpeg --with-webp \
+    && docker-php-ext-install -j"$(nproc)" \
+        pdo_mysql \
+        intl \
+        bcmath \
+        gd \
+        zip \
+        pcntl \
+        posix \
+        exif \
+        sockets \
+        opcache
+
+RUN pecl install redis \
+    && docker-php-ext-enable redis
+
+COPY --from=composer:2 /usr/bin/composer /usr/local/bin/composer
+
+RUN groupmod -g ${GID} www-data \
+    && usermod -u ${UID} -g ${GID} www-data \
+    && mkdir -p /var/www/.composer \
+    && chown -R www-data:www-data /var/www
+
+COPY php.ini       /usr/local/etc/php/conf.d/zz-app.ini
+COPY opcache.ini   /usr/local/etc/php/conf.d/zz-opcache.ini
+COPY php-fpm.conf  /usr/local/etc/php-fpm.d/zz-app.conf
+COPY entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+WORKDIR /var/www/html
+USER www-data
+
+EXPOSE 9000
+
+ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
+CMD ["php-fpm"]