feat(logging): deepen coordinator and core logging (NCS-72)

Coordinator: InstanceRegistry logs instance join/update/dead/remove;
CoordinatorGrpcServer logs new stream + first heartbeat per instance;
CoreGrpcClient logs channel open/evict and RPC success counts.

Core: GameResource replaces println with logger; RedisGameRegistry
logs store/Redis-load/DB-load and surfaces silent failures;
CoordinatorServiceHandler logs inbound gRPC commands; IoGrpcClientWrapper
and RuleSetGrpcAdapter wrap gRPC calls with WARN on failure.

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

modules/coordinator/src/main/resources/application.yml

@@ -9,7 +9,6 @@ quarkus:
     server:
       port: 9086
   rest-client:
-    connection-timeout: 5000
     read-timeout: 10000
   smallrye-openapi:
     info-title: NowChess Coordinator Service

modules/coordinator/src/main/scala/de/nowchess/coordinator/grpc/CoordinatorGrpcServer.scala

@@ -27,13 +27,24 @@ class CoordinatorGrpcServer extends CoordinatorServiceGrpc.CoordinatorServiceImp
   override def heartbeatStream(
       responseObserver: StreamObserver[CoordinatorCommand],
   ): StreamObserver[HeartbeatFrame] =
+    log.info("New heartbeat stream connection established")
     new StreamObserver[HeartbeatFrame]:
       // scalafix:off DisableSyntax.var
       private var lastInstanceId = ""
+      private var firstFrameSeen = false
       // scalafix:on DisableSyntax.var
 
       override def onNext(frame: HeartbeatFrame): Unit =
         lastInstanceId = frame.getInstanceId
+        if !firstFrameSeen then
+          firstFrameSeen = true
+          log.infof(
+            "First heartbeat from instance %s (host=%s http=%d grpc=%d)",
+            frame.getInstanceId,
+            frame.getHostname,
+            frame.getHttpPort,
+            frame.getGrpcPort,
+          )
         instanceRegistry
           .updateInstanceFromRedis(frame.getInstanceId)
           .subscribe()

modules/coordinator/src/main/scala/de/nowchess/coordinator/grpc/CoreGrpcClient.scala

@@ -16,10 +16,18 @@ class CoreGrpcClient:
   private val channels = ConcurrentHashMap[String, ManagedChannel]()
 
   private def getChannel(host: String, port: Int): ManagedChannel =
-    channels.computeIfAbsent(s"$host:$port", _ => ManagedChannelBuilder.forAddress(host, port).usePlaintext().build())
+    channels.computeIfAbsent(
+      s"$host:$port",
+      _ =>
+        log.infof("Opening gRPC channel to %s:%d", host, port)
+        ManagedChannelBuilder.forAddress(host, port).usePlaintext().build(),
+    )
 
   private def evictStaleChannel(host: String, port: Int): Unit =
-    Option(channels.remove(s"$host:$port")).foreach(_.shutdownNow())
+    Option(channels.remove(s"$host:$port")).foreach { ch =>
+      log.infof("Evicting stale gRPC channel to %s:%d", host, port)
+      ch.shutdownNow()
+    }
 
   @PreDestroy
   def shutdown(): Unit =
@@ -33,7 +41,9 @@ class CoreGrpcClient:
     try
       val stub    = CoordinatorServiceGrpc.newBlockingStub(getChannel(host, port))
       val request = BatchResubscribeRequest.newBuilder().addAllGameIds(gameIds.asJava).build()
-      stub.batchResubscribeGames(request).getSubscribedCount
+      val count   = stub.batchResubscribeGames(request).getSubscribedCount
+      log.debugf("batchResubscribeGames %s:%d — subscribed %d games", host, port, count)
+      count
     catch
       case ex: Exception =>
         log.warnf(ex, "batchResubscribeGames RPC failed for %s:%d", host, port)
@@ -44,7 +54,9 @@ class CoreGrpcClient:
     try
       val stub    = CoordinatorServiceGrpc.newBlockingStub(getChannel(host, port))
       val request = UnsubscribeGamesRequest.newBuilder().addAllGameIds(gameIds.asJava).build()
-      stub.unsubscribeGames(request).getUnsubscribedCount
+      val count   = stub.unsubscribeGames(request).getUnsubscribedCount
+      log.debugf("unsubscribeGames %s:%d — unsubscribed %d games", host, port, count)
+      count
     catch
       case ex: Exception =>
         log.warnf(ex, "unsubscribeGames RPC failed for %s:%d", host, port)
@@ -55,7 +67,9 @@ class CoreGrpcClient:
     try
       val stub    = CoordinatorServiceGrpc.newBlockingStub(getChannel(host, port))
       val request = EvictGamesRequest.newBuilder().addAllGameIds(gameIds.asJava).build()
-      stub.evictGames(request).getEvictedCount
+      val count   = stub.evictGames(request).getEvictedCount
+      log.debugf("evictGames %s:%d — evicted %d games", host, port, count)
+      count
     catch
       case ex: Exception =>
         log.warnf(ex, "evictGames RPC failed for %s:%d", host, port)

modules/coordinator/src/main/scala/de/nowchess/coordinator/service/InstanceRegistry.scala

@@ -41,19 +41,30 @@ class InstanceRegistry:
       .transformToUni { value =>
         try
           val metadata = mapper.readValue(value, classOf[InstanceMetadata])
+          val isNew    = !instances.containsKey(instanceId)
           instances.put(instanceId, metadata)
+          if isNew then
+            log.infof("Instance %s joined registry (subscriptions=%d)", instanceId, metadata.subscriptionCount)
+          else
+            log.debugf(
+              "Instance %s updated (subscriptions=%d state=%s)",
+              instanceId,
+              metadata.subscriptionCount,
+              metadata.state,
+            )
           Uni.createFrom().item(())
-        catch case ex: Exception =>
-          log.warnf(ex, "Failed to parse instance metadata for %s", instanceId)
-          Uni.createFrom().item(())
+        catch
+          case ex: Exception =>
+            log.warnf(ex, "Failed to parse instance metadata for %s", instanceId)
+            Uni.createFrom().item(())
       }
       .onFailure()
       .recoverWithItem(())
 
   def markInstanceDead(instanceId: String): Unit =
     instances.computeIfPresent(instanceId, (_, inst) => inst.copy(state = "DEAD"))
-    ()
+    log.infof("Instance %s marked dead", instanceId)
 
   def removeInstance(instanceId: String): Unit =
     instances.remove(instanceId)
-    ()
+    log.infof("Instance %s removed from registry", instanceId)