feat: Add option to disable early mode (v0.4.2)

- Add wp_prometheus_disable_early_mode option in admin settings
- Support WP_PROMETHEUS_DISABLE_EARLY_MODE environment variable
- Add Early Mode section in Metrics tab with status indicator
- Allow users to enable wp_prometheus_collect_metrics hook

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: 0.4.1
+ * Version: 0.4.2
  * Requires at least: 6.4
  * Requires PHP: 8.3
  * Author: Marco Graetsch
@@ -37,6 +37,18 @@ function wp_prometheus_early_metrics_check(): void {
         return;
     }
 
+    // Check if early mode is disabled via environment variable.
+    $env_disable = getenv( 'WP_PROMETHEUS_DISABLE_EARLY_MODE' );
+    if ( false !== $env_disable && in_array( strtolower( $env_disable ), array( '1', 'true', 'yes', 'on' ), true ) ) {
+        return;
+    }
+
+    // Check if early mode is disabled via option.
+    // We can use get_option() here because WordPress core is already loaded.
+    if ( get_option( 'wp_prometheus_disable_early_mode', false ) ) {
+        return;
+    }
+
     // Check if autoloader exists.
     $autoloader = __DIR__ . '/vendor/autoload.php';
     if ( ! file_exists( $autoloader ) ) {
@@ -118,7 +130,7 @@ wp_prometheus_early_metrics_check();
  *
  * @var string
  */
-define( 'WP_PROMETHEUS_VERSION', '0.4.1' );
+define( 'WP_PROMETHEUS_VERSION', '0.4.2' );
 
 /**
  * Plugin file path.