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- Deleted outdated `ApplicationConfiguration` and `HorseRepositoryImpl` classes.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

@@ -0,0 +1,38 @@
+plugins {
+  alias(libs.plugins.kotlinJvm)
+  alias(libs.plugins.kotlinSpring)
+  alias(libs.plugins.spring.boot)
+  alias(libs.plugins.spring.dependencyManagement)
+}
+
+springBoot {
+  mainClass.set("at.mocode.clubs.service.ClubsServiceApplicationKt")
+}
+
+dependencies {
+  implementation(projects.platform.platformDependencies)
+  implementation(projects.core.coreDomain)
+  implementation(projects.core.coreUtils)
+  implementation(projects.clubs.clubsDomain)
+  implementation(projects.clubs.clubsInfrastructure)
+
+  implementation(libs.spring.boot.starter.web)
+  implementation(libs.spring.boot.starter.validation)
+  implementation(libs.spring.boot.starter.actuator)
+
+  implementation(libs.exposed.core)
+  implementation(libs.exposed.dao)
+  implementation(libs.exposed.jdbc)
+  implementation(libs.exposed.kotlin.datetime)
+  implementation(libs.hikari.cp)
+  runtimeOnly(libs.postgresql.driver)
+  testRuntimeOnly(libs.h2.driver)
+
+  testImplementation(projects.platform.platformTesting)
+  testImplementation(libs.spring.boot.starter.test)
+  testImplementation(libs.logback.classic)
+}
+
+tasks.test {
+  useJUnitPlatform()
+}