feat(16-04): add Collector interface and RouterOSCollector

- Define Collector interface with Collect(ctx, dev, pub) error signature
- Implement RouterOSCollector as thin wrapper delegating to PollDevice
- Add compile-time interface assertion for RouterOSCollector

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

poller/internal/poller/collector.go

@@ -0,0 +1,19 @@
+package poller
+
+import (
+	"context"
+
+	"github.com/staack/the-other-dude/poller/internal/bus"
+	"github.com/staack/the-other-dude/poller/internal/store"
+)
+
+// Collector defines the contract for device-type-specific data collection.
+// Each device type (RouterOS, SNMP) implements this interface.
+// The Scheduler dispatches to the appropriate Collector based on device_type.
+type Collector interface {
+	// Collect performs one complete poll cycle for a device.
+	// It handles lock acquisition, credential decryption, connection,
+	// data collection, and event publishing.
+	// Returns ErrDeviceOffline if the device cannot be reached.
+	Collect(ctx context.Context, dev store.Device, pub *bus.Publisher) error
+}

poller/internal/poller/routeros_collector.go

@@ -0,0 +1,48 @@
+package poller
+
+import (
+	"context"
+	"time"
+
+	"github.com/bsm/redislock"
+
+	"github.com/staack/the-other-dude/poller/internal/bus"
+	"github.com/staack/the-other-dude/poller/internal/store"
+	"github.com/staack/the-other-dude/poller/internal/vault"
+)
+
+// RouterOSCollector implements Collector for MikroTik RouterOS devices.
+// It wraps the existing PollDevice logic, preserving identical behavior.
+type RouterOSCollector struct {
+	locker          *redislock.Client
+	credentialCache *vault.CredentialCache
+	connTimeout     time.Duration
+	cmdTimeout      time.Duration
+	lockTTL         time.Duration
+}
+
+// NewRouterOSCollector creates a RouterOSCollector with the given dependencies.
+func NewRouterOSCollector(
+	locker *redislock.Client,
+	credentialCache *vault.CredentialCache,
+	connTimeout time.Duration,
+	cmdTimeout time.Duration,
+	lockTTL time.Duration,
+) *RouterOSCollector {
+	return &RouterOSCollector{
+		locker:          locker,
+		credentialCache: credentialCache,
+		connTimeout:     connTimeout,
+		cmdTimeout:      cmdTimeout,
+		lockTTL:         lockTTL,
+	}
+}
+
+// Collect performs one RouterOS poll cycle. This is a thin wrapper around
+// PollDevice -- all business logic remains in worker.go unchanged.
+func (c *RouterOSCollector) Collect(ctx context.Context, dev store.Device, pub *bus.Publisher) error {
+	return PollDevice(ctx, dev, c.locker, pub, c.credentialCache, c.connTimeout, c.cmdTimeout, c.lockTTL)
+}
+
+// Compile-time interface assertion.
+var _ Collector = (*RouterOSCollector)(nil)