Add Docker Compose production stack (php-apache, mariadb, node/pm2)

Single-command deploy: docker compose up -d --build brings up the LEMP
stack plus the Node realtime/scheduler service. app/config.php and DB
secrets are generated from .env at container start, never baked into
the image or committed.

.gitignore

@@ -6,6 +6,9 @@ app/uploads
 node_modules/
 nodejs/.env
 
+# Docker deploy secrets
+/.env
+
 # zxcvbn dev dependencies (not needed at runtime)
 lib/zxcvbn-php-master/vendor/sebastian/