Week 1 infrastructure: Docker environments, deploy pipeline, bookstore-core scaffold

Docker Compose environments for dev/staging/production (MariaDB, Redis,
Caddy, Action Scheduler cron sidecar), an idempotent deploy script,
git-hook-based deploy pipeline, backup/restore scripts, and the
bookstore-core plugin stub with WooCommerce HPOS compatibility declared.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker/caddy/Caddyfile.dev

@@ -0,0 +1,10 @@
+:80 {
+	root * /var/www/html
+
+	request_body {
+		max_size 32MB
+	}
+
+	php_fastcgi wordpress:9000
+	file_server
+}