feat(18-05): wire SNMPCollector into Scheduler and main.go

- Add RegisterCollector method to Scheduler for external collector registration
- Initialize ProfileCache with 5-min refresh in main.go
- Initialize CounterCache using existing Redis client
- Create and register SNMPCollector as "snmp" in scheduler
- Start DiscoveryResponder for NATS SNMP device auto-detection
- Existing RouterOS polling path completely unaffected

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poller/cmd/poller/main.go

@@ -22,6 +22,7 @@ import (
 	"github.com/staack/the-other-dude/poller/internal/config"
 	"github.com/staack/the-other-dude/poller/internal/observability"
 	"github.com/staack/the-other-dude/poller/internal/poller"
+	"github.com/staack/the-other-dude/poller/internal/snmp"
 	"github.com/staack/the-other-dude/poller/internal/sshrelay"
 	"github.com/staack/the-other-dude/poller/internal/store"
 	"github.com/staack/the-other-dude/poller/internal/tunnel"
@@ -267,6 +268,33 @@ func main() {
 		maxBackoff,
 	)
 
+	// -----------------------------------------------------------------------
+	// Initialize SNMP components (profile cache, counter cache, collector)
+	// -----------------------------------------------------------------------
+	profileCache := snmp.NewProfileCache(deviceStore.Pool(), 5*time.Minute)
+	if err := profileCache.Load(ctx); err != nil {
+		slog.Warn("initial SNMP profile cache load failed (SNMP polling will start after first refresh)", "error", err)
+	}
+	go profileCache.StartRefresh(ctx)
+
+	counterCache := snmp.NewCounterCache(redisClient)
+
+	snmpCollector := snmp.NewSNMPCollector(profileCache, credentialCache, counterCache, snmp.DefaultSNMPConfig())
+	scheduler.RegisterCollector("snmp", snmpCollector)
+
+	slog.Info("SNMP collector registered",
+		"profile_refresh_interval", "5m",
+	)
+
+	// -----------------------------------------------------------------------
+	// Initialize SNMP discovery responder (NATS request-reply)
+	// -----------------------------------------------------------------------
+	discoveryResponder := bus.NewDiscoveryResponder(publisher.Conn())
+	if err := discoveryResponder.Start(); err != nil {
+		slog.Error("failed to start SNMP discovery responder", "error", err)
+	}
+	defer discoveryResponder.Stop()
+
 	slog.Info("starting device scheduler",
 		"poll_interval", pollInterval,
 		"refresh_period", refreshPeriod,

poller/internal/poller/scheduler.go

@@ -87,12 +87,19 @@ func NewScheduler(
 		activeDevices:   make(map[string]*deviceState),
 	}
 
-	// Register built-in collectors. Future device types (SNMP) register here.
+	// Register built-in collectors.
 	s.collectors["routeros"] = NewRouterOSCollector(locker, credentialCache, connTimeout, cmdTimeout, lockTTL)
 
 	return s
 }
 
+// RegisterCollector adds a named Collector to the scheduler's dispatch map.
+// This allows external packages (e.g., SNMP) to register collectors without
+// modifying NewScheduler's parameter list.
+func (s *Scheduler) RegisterCollector(name string, c Collector) {
+	s.collectors[name] = c
+}
+
 // Run is the main scheduler loop. It:
 //  1. Fetches devices from the database.
 //  2. Starts goroutines for newly-discovered devices.