feat: implement self-signed certificate support in API and UI

- Added support for self-signed TLS certificates in the ApiService, allowing configuration based on server settings.
- Introduced a toggle in the ServerConnectionPage to enable or disable trusting self-signed certificates.
- Updated localization files to include new strings for self-signed certificate settings in multiple languages.
- Enhanced the OptimizedStorageService to manage trusted servers based on user preferences for self-signed certificates.
- Improved error handling and logging throughout the affected services to ensure clarity and maintainability.

lib/l10n/app_localizations_de.dart

@@ -760,6 +760,14 @@ class AppLocalizationsDe extends AppLocalizations {
   String get customHeadersDescription =>
       'Füge benutzerdefinierte HTTP-Header für Authentifizierung, API-Schlüssel oder spezielle Serveranforderungen hinzu.';
 
+  @override
+  String get allowSelfSignedCertificates =>
+      'Selbstsignierten Zertifikaten vertrauen';
+
+  @override
+  String get allowSelfSignedCertificatesDescription =>
+      'Akzeptiere das TLS-Zertifikat dieses Servers auch dann, wenn es selbstsigniert ist. Aktiviere diese Option nur für Server, denen du vertraust.';
+
   @override
   String get headerNameEmpty => 'Header-Name darf nicht leer sein';