feat(v1.8.0): IMPL_01 Language Settings - Smooth Language Switching

- Prevent activity recreate during language changes via configChanges
- Add onConfigurationChanged() handler in ComposeSettingsActivity
- Simplify setAppLanguage() - let system handle locale change smoothly
- Update language_info strings to reflect smooth transition
- Remove unused Activity parameter and imports

Fixes flicker during language switching by handling configuration
changes instead of recreating the entire activity. Compose recomposes
automatically when locale changes, providing seamless UX.

android/app/src/main/res/values-de/strings.xml

@@ -409,7 +409,7 @@
     <string name="language_system_default">Systemstandard</string>
     <string name="language_english">English</string>
     <string name="language_german">Deutsch</string>
-    <string name="language_info">ℹ️ Wähle deine bevorzugte Sprache. Die App wird neu gestartet, um die Änderung anzuwenden.</string>
+    <string name="language_info">ℹ️ Wähle deine bevorzugte Sprache. Die Ansicht wird kurz aktualisiert, um die Änderung anzuwenden.</string>
     <string name="language_changed_restart">Sprache geändert. Neustart…</string>
     
     <!-- ============================= -->

android/app/src/main/res/values/strings.xml

@@ -409,7 +409,7 @@
     <string name="language_system_default">System Default</string>
     <string name="language_english">English</string>
     <string name="language_german">Deutsch</string>
-    <string name="language_info">ℹ️ Choose your preferred language. The app will restart to apply the change.</string>
+    <string name="language_info">ℹ️ Choose your preferred language. The view will briefly refresh to apply the change.</string>
     <string name="language_changed_restart">Language changed. Restarting…</string>
     
     <!-- ============================= -->