feat: Add WooCommerce, cron, and transient metrics (v0.2.0)

- WooCommerce integration metrics (products, orders, revenue, customers)
- Cron job metrics (events by hook, overdue count, next run timestamp)
- Transient cache metrics (total, expiring, expired)
- Support for WooCommerce HPOS storage
- Updated settings page with new metric categories
- Updated translations and documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -92,6 +92,33 @@ scrape_configs:
 
 **Note:** Runtime metrics aggregate data across requests. Enable only the metrics you need to minimize performance impact.
 
+### Cron Metrics (v0.2.0+)
+
+| Metric | Type | Labels | Description |
+|--------|------|--------|-------------|
+| wordpress_cron_events_total | Gauge | hook | Scheduled cron events by hook |
+| wordpress_cron_overdue_total | Gauge | - | Number of overdue cron events |
+| wordpress_cron_next_run_timestamp | Gauge | - | Unix timestamp of next scheduled cron |
+
+### Transient Metrics (v0.2.0+)
+
+| Metric | Type | Labels | Description |
+|--------|------|--------|-------------|
+| wordpress_transients_total | Gauge | type | Transients by type (total, with_expiration, persistent, expired) |
+
+### WooCommerce Metrics (v0.2.0+)
+
+These metrics are only available when WooCommerce is active.
+
+| Metric | Type | Labels | Description |
+|--------|------|--------|-------------|
+| wordpress_woocommerce_products_total | Gauge | status, type | Products by status and type |
+| wordpress_woocommerce_orders_total | Gauge | status | Orders by status |
+| wordpress_woocommerce_revenue_total | Gauge | period, currency | Revenue (all_time, today, month) |
+| wordpress_woocommerce_customers_total | Gauge | type | Customers (registered, guest) |
+
+**Note:** WooCommerce metrics support both legacy post-based orders and HPOS (High-Performance Order Storage).
+
 ## Extending with Custom Metrics
 
 Add your own metrics using the `wp_prometheus_collect_metrics` action: