feat: Split Metrics tab into sub-tabs and fix early mode storage (v0.4.3)

- Add sub-tabs: Endpoint, Selection, Runtime, Advanced
- Fix early mode checkbox not saving (was outside form element)
- Add CSS styling for horizontal sub-tab navigation
- Update translations with new sub-tab strings

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

CHANGELOG.md

@@ -5,18 +5,24 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [0.4.2] - 2026-02-02
+## [0.4.3] - 2026-02-02
 
 ### Added
 
-- Option to disable early mode in admin settings (Metrics tab)
+- Sub-tabs navigation within Metrics tab (Endpoint, Selection, Runtime, Advanced)
+- Option to disable early mode in admin settings (Metrics → Advanced)
 - Support for `WP_PROMETHEUS_DISABLE_EARLY_MODE` environment variable
 - Early mode status display in settings
 
+### Fixed
+
+- Early mode setting now saves correctly (moved into form with proper settings group)
+
 ### Changed
 
-- Early mode can now be disabled for users who need the `wp_prometheus_collect_metrics` hook for custom metrics
-- Updated translations with new early mode strings (English and German)
+- Reorganized Metrics tab into logical sub-sections for better usability
+- Early mode can now be disabled for users who need the `wp_prometheus_collect_metrics` hook
+- Updated translations with sub-tab and early mode strings (English and German)
 
 ## [0.4.1] - 2026-02-02