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

.gitignore

@@ -4,6 +4,8 @@
 .settings
 .project
 .classpath
+application-secrets.properties
+.env
 
 *.iml
 .DS_Store