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>

wp-content/plugins/bookstore-core/composer.json

@@ -0,0 +1,13 @@
+{
+    "name": "bookstore/bookstore-core",
+    "description": "Business logic plugin for the bookstore: catalog, pricing, supplier routing, order state.",
+    "type": "wordpress-plugin",
+    "require": {
+        "php": ">=8.1"
+    },
+    "autoload": {
+        "psr-4": {
+            "Bookstore\\Core\\": "includes/"
+        }
+    }
+}