feat(12-01): add RF monitor collector, WIRELESS_REGISTRATIONS stream, wire into poll cycle

- RFMonitorStats struct for per-interface RF data (noise floor, channel width, TX power)
- CollectRFMonitor with v6/v7 RouterOS version routing
- WIRELESS_REGISTRATIONS NATS stream with 30-day retention (separate from DEVICE_EVENTS)
- WirelessRegistrationEvent type and PublishWirelessRegistrations method
- Poll cycle collects per-client registrations and RF stats, publishes combined event

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

poller/internal/device/rf_monitor.go

@@ -0,0 +1,107 @@
+package device
+
+import (
+	"log/slog"
+	"strconv"
+
+	routeros "github.com/go-routeros/routeros/v3"
+)
+
+// RFMonitorStats holds per-interface RF monitoring data collected from
+// the RouterOS monitor command. These stats describe the RF environment
+// rather than individual clients.
+type RFMonitorStats struct {
+	Interface         string `json:"interface"`
+	NoiseFloor        int    `json:"noise_floor"`         // dBm, e.g. -105
+	ChannelWidth      string `json:"channel_width"`       // e.g. "20MHz", "40MHz"
+	TxPower           int    `json:"tx_power"`            // dBm, e.g. 24
+	RegisteredClients int    `json:"registered_clients"`  // count from monitor
+}
+
+// CollectRFMonitor queries the RouterOS device for per-interface RF statistics
+// using the monitor command.
+//
+// Version routing:
+//   - majorVersion >= 7: runs /interface/wifi/print to list interfaces, then
+//     /interface/wifi/monitor for each interface.
+//   - majorVersion < 7: runs /interface/wireless/print to list interfaces,
+//     then /interface/wireless/monitor for each interface.
+//
+// Returns nil, nil when the device has no wireless interfaces.
+func CollectRFMonitor(client *routeros.Client, majorVersion int) ([]RFMonitorStats, error) {
+	var printCmd, monitorCmd string
+
+	if majorVersion >= 7 {
+		printCmd = "/interface/wifi/print"
+		monitorCmd = "/interface/wifi/monitor"
+	} else {
+		printCmd = "/interface/wireless/print"
+		monitorCmd = "/interface/wireless/monitor"
+	}
+
+	// List wireless interface names.
+	listReply, err := client.Run(printCmd, "=.proplist=name")
+	if err != nil {
+		slog.Debug("device has no wireless interfaces for RF monitor", "error", err)
+		return nil, nil
+	}
+
+	if len(listReply.Re) == 0 {
+		return nil, nil
+	}
+
+	stats := make([]RFMonitorStats, 0, len(listReply.Re))
+	for _, s := range listReply.Re {
+		ifaceName := s.Map["name"]
+		if ifaceName == "" {
+			continue
+		}
+
+		// Run monitor command for this interface.
+		monReply, monErr := client.Run(monitorCmd, "=numbers="+ifaceName, "=once=")
+		if monErr != nil {
+			slog.Debug("RF monitor command failed for interface",
+				"interface", ifaceName, "command", monitorCmd, "error", monErr)
+			continue
+		}
+
+		if len(monReply.Re) == 0 {
+			continue
+		}
+
+		m := monReply.Re[0].Map
+		entry := RFMonitorStats{
+			Interface: ifaceName,
+		}
+
+		// Noise floor.
+		if nf, parseErr := strconv.Atoi(m["noise-floor"]); parseErr == nil {
+			entry.NoiseFloor = nf
+		}
+
+		// Channel width: v6 uses "channel-width", v7 may use "channel" with width embedded.
+		if majorVersion >= 7 {
+			entry.ChannelWidth = m["channel"]
+		} else {
+			entry.ChannelWidth = m["channel-width"]
+		}
+
+		// TX power.
+		if txp, parseErr := strconv.Atoi(m["tx-power"]); parseErr == nil {
+			entry.TxPower = txp
+		}
+
+		// Registered clients count.
+		if rc, parseErr := strconv.Atoi(m["registered-clients"]); parseErr == nil {
+			entry.RegisteredClients = rc
+		}
+
+		stats = append(stats, entry)
+	}
+
+	if len(stats) == 0 {
+		return nil, nil
+	}
+
+	return stats, nil
+}

poller/internal/device/rf_monitor_test.go

@@ -0,0 +1,32 @@
+package device
+
+import (
+	"testing"
+)
+
+func TestRFMonitorStatsFields(t *testing.T) {
+	// Compilation test: ensure RFMonitorStats has all required fields
+	// with correct types.
+	stats := RFMonitorStats{
+		Interface:         "wlan1",
+		NoiseFloor:        -105,
+		ChannelWidth:      "20MHz",
+		TxPower:           24,
+		RegisteredClients: 15,
+	}
+	if stats.Interface != "wlan1" {
+		t.Error("Interface field not set correctly")
+	}
+	if stats.NoiseFloor != -105 {
+		t.Error("NoiseFloor field not set correctly")
+	}
+	if stats.ChannelWidth != "20MHz" {
+		t.Error("ChannelWidth field not set correctly")
+	}
+	if stats.TxPower != 24 {
+		t.Error("TxPower field not set correctly")
+	}
+	if stats.RegisteredClients != 15 {
+		t.Error("RegisteredClients field not set correctly")
+	}
+}