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>

CLAUDE.md

@@ -291,6 +291,24 @@ add_action( 'wp_prometheus_collect_metrics', function( $collector ) {
 
 ## Session History
 
+### 2026-02-02 - Early Mode Toggle (v0.4.2)
+
+- Added option to disable early mode for users who need extensibility
+- Implementation:
+  - Added `wp_prometheus_disable_early_mode` WordPress option
+  - Added `WP_PROMETHEUS_DISABLE_EARLY_MODE` environment variable support
+  - Option check in `wp_prometheus_early_metrics_check()` before early interception
+  - Environment variable accepts `1`, `true`, `yes`, `on` (case-insensitive)
+- Admin UI in Metrics tab:
+  - "Early Mode" section with description of functionality
+  - Checkbox to disable early metrics interception
+  - Environment override notice when env var is set
+  - Current status indicator showing early mode state
+- **Key Learning**: Balancing compatibility vs extensibility
+  - Early mode fixes memory issues but disables `wp_prometheus_collect_metrics` hook
+  - Users with custom metrics need the hook, so early mode must be optional
+  - Default remains enabled (safe) with explicit opt-out for advanced users
+
 ### 2026-02-02 - Plugin Compatibility Fix (v0.4.1)
 
 - Fixed memory exhaustion (1GB limit) when wp-fedistream (Twig-based) plugin is active