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>

languages/wp-prometheus-de_CH.po

@@ -919,3 +919,31 @@ msgstr "Fruehzeitiger Modus ist aktiviert (aktiv fuer /metrics-Anfragen)"
 #: src/Admin/Settings.php
 msgid "Clear all accumulated runtime metric data (HTTP requests, database queries). This is useful for testing or starting fresh."
 msgstr "Alle gesammelten Laufzeit-Metrikdaten loeschen (HTTP-Anfragen, Datenbank-Abfragen). Dies ist nuetzlich zum Testen oder fuer einen Neuanfang."
+
+#: src/Admin/Settings.php
+msgid "Endpoint"
+msgstr "Endpunkt"
+
+#: src/Admin/Settings.php
+msgid "Selection"
+msgstr "Auswahl"
+
+#: src/Admin/Settings.php
+msgid "Runtime"
+msgstr "Laufzeit"
+
+#: src/Admin/Settings.php
+msgid "Advanced"
+msgstr "Erweitert"
+
+#: src/Admin/Settings.php
+msgid "Runtime Metrics Management"
+msgstr "Laufzeit-Metriken Verwaltung"
+
+#: src/Admin/Settings.php
+msgid "Runtime metrics track HTTP requests and database queries across requests. Use this section to manage accumulated data."
+msgstr "Laufzeit-Metriken erfassen HTTP-Anfragen und Datenbank-Abfragen ueber mehrere Anfragen hinweg. Verwenden Sie diesen Bereich zur Verwaltung der gesammelten Daten."
+
+#: src/Admin/Settings.php
+msgid "Reset Data"
+msgstr "Daten zuruecksetzen"

languages/wp-prometheus.pot

@@ -916,3 +916,31 @@ msgstr ""
 #: src/Admin/Settings.php
 msgid "Clear all accumulated runtime metric data (HTTP requests, database queries). This is useful for testing or starting fresh."
 msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Endpoint"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Selection"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Runtime"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Advanced"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Runtime Metrics Management"
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Runtime metrics track HTTP requests and database queries across requests. Use this section to manage accumulated data."
+msgstr ""
+
+#: src/Admin/Settings.php
+msgid "Reset Data"
+msgstr ""