fix: Resolve memory exhaustion with Twig-based plugins (v0.4.1)

- Add early metrics endpoint handler to intercept /metrics before full WP init
- Remove content filters during metrics collection to prevent recursion
- Skip extensibility hooks in early metrics mode
- Change template_redirect to parse_request for earlier interception

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

src/Metrics/Collector.php

@@ -121,9 +121,14 @@ class Collector {
         /**
          * Fires after default metrics are collected.
          *
+         * Skip in early metrics mode to avoid triggering third-party hooks
+         * that may cause recursion issues (e.g., Twig-based plugins).
+         *
          * @param Collector $collector The metrics collector instance.
          */
-        do_action( 'wp_prometheus_collect_metrics', $this );
+        if ( ! defined( 'WP_PROMETHEUS_EARLY_METRICS' ) || ! WP_PROMETHEUS_EARLY_METRICS ) {
+            do_action( 'wp_prometheus_collect_metrics', $this );
+        }
     }
 
     /**