fix(auth): add InternalClientHeadersFactory for custom client headers management

modules/security/src/main/scala/de/nowchess/security/InternalClientHeadersFactory.scala

@@ -0,0 +1,27 @@
+package de.nowchess.security
+
+import jakarta.enterprise.context.ApplicationScoped
+import jakarta.ws.rs.core.MultivaluedMap
+import org.eclipse.microprofile.config.inject.ConfigProperty
+import org.eclipse.microprofile.rest.client.ext.DefaultClientHeadersFactoryImpl
+
+import scala.compiletime.uninitialized
+
+@ApplicationScoped
+class InternalClientHeadersFactory extends DefaultClientHeadersFactoryImpl {
+
+  @ConfigProperty(name = "nowchess.internal.secret", defaultValue = "")
+  // scalafix:off DisableSyntax.var
+  var secret: String = uninitialized
+
+  @ConfigProperty(name = "nowchess.internal.auth.enabled", defaultValue = "true")
+  var authEnabled: Boolean = uninitialized
+  // scalafix:on DisableSyntax.var
+
+  override def update(incomingHeaders: MultivaluedMap[String, String], clientOutgoingHeaders: MultivaluedMap[String, String]): MultivaluedMap[String, String] = {
+    val default = super.update(incomingHeaders, clientOutgoingHeaders)
+    default.putSingle("X-Internal-Secret", secret)
+    default
+  }
+
+}