feat: add periodic health check to evict dead instances

Add quarkus-scheduler dependency and schedule health check every 10 seconds.
Dead instances (marked with state="DEAD") now automatically evicted instead of
accumulating indefinitely.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

modules/coordinator/build.gradle.kts

@@ -78,6 +78,7 @@ dependencies {
     implementation("com.fasterxml.jackson.module:jackson-module-scala_3:${versions["JACKSON_SCALA"]!!}")
     implementation("io.quarkus:quarkus-redis-client")
     implementation("io.quarkus:quarkus-kubernetes-client")
+    implementation("io.quarkus:quarkus-scheduler")
 
     testImplementation(platform("org.junit:junit-bom:${versions["JUNIT_BOM"]!!}"))
     testImplementation("org.junit.jupiter:junit-jupiter")