feat: Reorganize settings page with tabbed interface (v0.1.1)

- Add tabbed navigation (License, Metrics, Help)
- Move Prometheus configuration to dedicated Help tab
- Separate static and runtime metrics with descriptions
- Add admin CSS for tab styling
- Add endpoint info, curl examples, and metrics reference in Help tab

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

wp-prometheus.php

@@ -3,7 +3,7 @@
  * Plugin Name: WP Prometheus
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wp-prometheus
  * Description: Prometheus metrics endpoint for WordPress with extensible hooks for custom metrics.
- * Version: 0.1.0
+ * Version: 0.1.1
  * Requires at least: 6.4
  * Requires PHP: 8.3
  * Author: Marco Graetsch
@@ -26,7 +26,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  *
  * @var string
  */
-define( 'WP_PROMETHEUS_VERSION', '0.1.0' );
+define( 'WP_PROMETHEUS_VERSION', '0.1.1' );
 
 /**
  * Plugin file path.