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- Deleted outdated `ApplicationConfiguration` and `HorseRepositoryImpl` classes.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/persons/persons-infrastructure/build.gradle.kts

@@ -0,0 +1,23 @@
+plugins {
+  alias(libs.plugins.kotlinJvm)
+  alias(libs.plugins.kotlinSpring)
+  alias(libs.plugins.kotlinSerialization)
+}
+
+dependencies {
+  implementation(projects.platform.platformDependencies)
+  implementation(projects.persons.personsDomain)
+  implementation(projects.core.coreDomain)
+  implementation(projects.core.coreUtils)
+
+  implementation(libs.spring.boot.starter.web)
+
+  implementation(libs.exposed.core)
+  implementation(libs.exposed.dao)
+  implementation(libs.exposed.jdbc)
+  implementation(libs.exposed.kotlin.datetime)
+
+  runtimeOnly(libs.postgresql.driver)
+
+  testImplementation(projects.platform.platformTesting)
+}

backend/services/persons/persons-infrastructure/src/main/kotlin/at/mocode/persons/infrastructure/persistence/ZnsPersonTable.kt

@@ -0,0 +1,23 @@
+package at.mocode.persons.infrastructure.persistence
+
+import org.jetbrains.exposed.v1.core.dao.id.java.UUIDTable
+import org.jetbrains.exposed.v1.datetime.date
+import org.jetbrains.exposed.v1.datetime.timestamp
+
+/**
+ * Tabelle für importierte Personen/Reiter aus dem ZNS-Datenbestand (LIZENZ01.dat).
+ * Wird ausschließlich als Dev-Seed-Daten verwendet.
+ */
+object ZnsPersonTable : UUIDTable("zns_persons") {
+  val lizenzNummer = varchar("lizenz_nummer", 10).uniqueIndex()
+  val nachname = varchar("nachname", 50)
+  val vorname = varchar("vorname", 25)
+  val vereinsNummer = varchar("vereins_nummer", 4).nullable()
+  val vereinsName = varchar("vereins_name", 50).nullable()
+  val nation = varchar("nation", 3).nullable()
+  val lizenzKlasse = varchar("lizenz_klasse", 6).nullable()
+  val mitgliedsNummer = varchar("mitglieds_nummer", 13).nullable()
+  val geschlecht = varchar("geschlecht", 1).nullable()
+  val geburtsdatum = date("geburtsdatum").nullable()
+  val createdAt = timestamp("created_at")
+}