feat: wire Metrics into service + add metrics.snapshot action

Every synced block increments blocks_processed counter.
Alias registrations increment aliases_found counter.
Sync errors tracked separately.

blockchain.metrics.snapshot returns all counters atomically.
43 total Core actions.

Co-Authored-By: Charon <charon@lethean.io>

actions.go

@@ -667,3 +667,10 @@ func makeEstHeightAtTime(ch *chain.Chain) core.ActionHandler {
 		return core.Result{Value: est, OK: true}
 	}
 }
+
+// RegisterMetricsActions registers operational metrics actions.
+func RegisterMetricsActions(c *core.Core, m *Metrics) {
+	c.Action("blockchain.metrics.snapshot", func(ctx context.Context, opts core.Options) core.Result {
+		return core.Result{Value: m.Snapshot(), OK: true}
+	})
+}

service.go

@@ -37,6 +37,7 @@ type BlockchainService struct {
 	store   *store.Store
 	daemon  *daemon.Server
 	events  *EventBus
+	metrics *Metrics
 	cancel  context.CancelFunc
 }
 
@@ -78,11 +79,14 @@ func (s *BlockchainService) start() core.Result {
 	s.store = st
 	s.chain = chain.New(st)
 	s.events = NewEventBus()
+	s.metrics = NewMetrics(s.chain)
 
-	// Wire block events
+	// Wire block events + metrics
 	s.chain.SetBlockCallback(func(height uint64, hash string, aliasName string) {
+		s.metrics.RecordBlock()
 		s.events.Emit(Event{Type: EventBlockNew, Height: height, Data: hash})
 		if aliasName != "" {
+			s.metrics.RecordAlias()
 			s.events.Emit(Event{Type: EventAlias, Height: height, Data: aliasName})
 		}
 	})