Add SIM card management and emulator container service

- Add SimCardAssignmentService for managing SIM card assignments
- Add SimCardConfigurationView for UI-based SIM card configuration
- Add EmulatorContainerService for container lifecycle management
- Add NiederlassungResolver for branch/location resolution
- Add new POJOs: CourierInfo and SimCardInfo
- Refactor security: introduce SsoConfiguration and LoginSessionService
- Remove deprecated AdminView and VaadinAccessHandler
- Add unit tests for core services

src/main/java/util/PreferencesKeyValueStore.java

@@ -1,20 +0,0 @@
-package util;
-
-import org.springframework.stereotype.Service;
-
-import java.util.Optional;
-import java.util.prefs.Preferences;
-
-@Service
-public class PreferencesKeyValueStore {
-
-    private final Preferences prefs = Preferences.userRoot().node("emulatorstation");
-
-    public void put(String key, String value) {
-        prefs.put(key, value);
-    }
-
-    public Optional<String> get(String key) {
-        return Optional.ofNullable(prefs.get(key, null));
-    }
-}