feat(horses-service): remove legacy configuration and repository classes

- Deleted outdated `ApplicationConfiguration` and `HorseRepositoryImpl` classes.
- Migrated to streamlined modular Gradle configuration in `build.gradle.kts`.
- Updated domain models and dependencies to use multiplatform and serialization plugins.
- Added modular setup for `horses` namespace in `settings.gradle.kts`.
- Reorganized database configuration with minimal JDBC bindings for development.

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

backend/services/clubs/clubs-service/src/main/kotlin/at/mocode/clubs/service/ClubsServiceApplication.kt

@@ -0,0 +1,18 @@
+package at.mocode.clubs.service
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+import org.springframework.context.annotation.ComponentScan
+
+@SpringBootApplication
+@ComponentScan(
+  basePackages = [
+    "at.mocode.clubs.service",
+    "at.mocode.clubs.infrastructure"
+  ]
+)
+class ClubsServiceApplication
+
+fun main(args: Array<String>) {
+  runApplication<ClubsServiceApplication>(*args)
+}

backend/services/clubs/clubs-service/src/main/kotlin/at/mocode/clubs/service/config/DatabaseConfiguration.kt

@@ -0,0 +1,31 @@
+package at.mocode.clubs.service.config
+
+import at.mocode.clubs.infrastructure.persistence.ZnsClubTable
+import jakarta.annotation.PostConstruct
+import org.jetbrains.exposed.v1.jdbc.Database
+import org.jetbrains.exposed.v1.jdbc.SchemaUtils
+import org.jetbrains.exposed.v1.jdbc.transactions.transaction
+import org.slf4j.LoggerFactory
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.context.annotation.Configuration
+import org.springframework.context.annotation.Profile
+
+@Configuration
+@Profile("dev")
+class ClubsDatabaseConfiguration(
+  @Value("\${spring.datasource.url}") private val jdbcUrl: String,
+  @Value("\${spring.datasource.username}") private val username: String,
+  @Value("\${spring.datasource.password}") private val password: String
+) {
+  private val log = LoggerFactory.getLogger(ClubsDatabaseConfiguration::class.java)
+
+  @PostConstruct
+  fun initializeDatabase() {
+    log.info("Initialisiere Datenbank-Schema für Clubs-Service...")
+    Database.connect(jdbcUrl, user = username, password = password)
+    transaction {
+      SchemaUtils.createMissingTablesAndColumns(ZnsClubTable)
+      log.info("Datenbank-Schema erfolgreich initialisiert")
+    }
+  }
+}

backend/services/clubs/clubs-service/src/main/kotlin/at/mocode/clubs/service/dev/ZnsClubSeeder.kt

@@ -0,0 +1,80 @@
+package at.mocode.clubs.service.dev
+
+import at.mocode.clubs.infrastructure.persistence.ZnsClubTable
+import org.jetbrains.exposed.v1.jdbc.SchemaUtils
+import org.jetbrains.exposed.v1.jdbc.batchInsert
+import org.jetbrains.exposed.v1.jdbc.transactions.transaction
+import org.slf4j.LoggerFactory
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.boot.CommandLineRunner
+import org.springframework.context.annotation.Profile
+import org.springframework.stereotype.Component
+import java.io.File
+import kotlin.time.Clock
+
+/**
+ * Dev-only Seeder: Importiert VEREIN01.dat (ZNS) → zns_clubs.
+ * Aktivierung: Umgebungsvariable ZNS_DATA_DIR setzen + Profil "dev".
+ */
+@Component
+@Profile("dev")
+class ZnsClubSeeder(
+  @Value("\${zns.data.dir:#{null}}") private val znsDataDir: String?
+) : CommandLineRunner {
+
+  private val log = LoggerFactory.getLogger(ZnsClubSeeder::class.java)
+
+  override fun run(vararg args: String) {
+    if (znsDataDir == null) {
+      log.info("ZNS_DATA_DIR nicht gesetzt – ZnsClubSeeder wird übersprungen.")
+      return
+    }
+    val dir = File(znsDataDir)
+    if (!dir.exists() || !dir.isDirectory) {
+      log.warn("ZNS_DATA_DIR '{}' existiert nicht oder ist kein Verzeichnis.", znsDataDir)
+      return
+    }
+    log.info("Starte ZNS-Vereine-Import aus: {}", dir.absolutePath)
+    transaction {
+      SchemaUtils.createMissingTablesAndColumns(ZnsClubTable)
+    }
+    seedClubs(dir)
+    log.info("ZNS-Vereine-Import abgeschlossen.")
+  }
+
+  // -------------------------------------------------------------------------
+  // VEREIN01.dat → zns_clubs
+  // Format:
+  //   [0-3]  VereinsNr (4 Zeichen)
+  //   [4-53] Name (50 Zeichen)
+  // -------------------------------------------------------------------------
+  private fun seedClubs(dir: File) {
+    val file = File(dir, "VEREIN01.dat")
+    if (!file.exists()) {
+      log.warn("VEREIN01.dat nicht gefunden – Vereine werden übersprungen.")
+      return
+    }
+
+    data class ClubRow(val nr: String, val name: String)
+
+    val rows = file.readLines(Charsets.ISO_8859_1)
+      .filter { it.length >= 4 }
+      .map { line ->
+        ClubRow(
+          nr = line.substring(0, 4).trim(),
+          name = line.substring(4).trim().take(50)
+        )
+      }
+      .filter { it.nr.isNotBlank() }
+
+    val now = Clock.System.now()
+    transaction {
+      ZnsClubTable.batchInsert(rows, ignore = true) { row ->
+        this[ZnsClubTable.vereinsNummer] = row.nr
+        this[ZnsClubTable.name] = row.name
+        this[ZnsClubTable.createdAt] = now
+      }
+    }
+    log.info("Vereine importiert: {} Datensätze", rows.size)
+  }
+}