chore: update module dependencies and remove unused imports

- Added `backend.infrastructure.persistence` to `@SpringBootApplication` scanBasePackages in `IdentityServiceApplication` and included it as a dependency in `build.gradle.kts`.
- Cleaned up unused imports in several files, including `Screens.kt`, `VeranstaltungScreens.kt`, and `TurnierAbrechnungTab.kt`.
- Updated `PingJpaEntity` to include `@Column` annotation for `createdAt` field.
- Refactored import ordering in `ZnsImportServiceTest` and `DatabaseFactory`.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

backend/services/ping/ping-service/src/main/kotlin/at/mocode/ping/infrastructure/persistence/PingJpaEntity.kt

@@ -1,10 +1,11 @@
 package at.mocode.ping.infrastructure.persistence
 
+import jakarta.persistence.Column
 import jakarta.persistence.Entity
 import jakarta.persistence.Id
 import jakarta.persistence.Table
 import java.time.Instant
-import java.util.UUID
+import java.util.*
 
 @Entity
 @Table(name = "ping")
@@ -12,6 +13,7 @@ class PingJpaEntity(
   @Id
   var id: UUID,
   var message: String,
+  @Column(name = "created_at")
   var createdAt: Instant
 ) {
 }