feat(12-01): add per-client wireless registration collector and signal parser

- RegistrationEntry struct for per-client wireless data (MAC, signal, CCQ, rates, distance)
- ParseSignalStrength handles all RouterOS format variations (-67, -67@5GHz, -67@HT40)
- CollectRegistrations with v6/v7 RouterOS version routing
- Unit tests for ParseSignalStrength covering 10 cases

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

poller/internal/device/registration_test.go

@@ -0,0 +1,64 @@
+package device
+
+import (
+	"testing"
+)
+
+func TestParseSignalStrength(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   string
+		want    int
+		wantErr bool
+	}{
+		{name: "plain negative", input: "-67", want: -67},
+		{name: "with 5GHz suffix", input: "-67@5GHz", want: -67},
+		{name: "with 2.4GHz suffix", input: "-72@2.4GHz", want: -72},
+		{name: "empty string", input: "", want: 0},
+		{name: "invalid string", input: "abc", want: 0, wantErr: true},
+		{name: "with HT40 suffix", input: "-67@HT40", want: -67},
+		{name: "with HT20 suffix", input: "-55@HT20", want: -55},
+		{name: "positive value", input: "10", want: 10},
+		{name: "zero", input: "0", want: 0},
+		{name: "with complex suffix", input: "-80@5GHz-Ce/a/ac/an", want: -80},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseSignalStrength(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseSignalStrength(%q) error = %v, wantErr %v", tt.input, err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("ParseSignalStrength(%q) = %d, want %d", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestRegistrationEntryFields(t *testing.T) {
+	// Compilation test: ensure RegistrationEntry has all required fields.
+	entry := RegistrationEntry{
+		Interface:        "wlan1",
+		MacAddress:       "AA:BB:CC:DD:EE:FF",
+		SignalStrength:   -67,
+		TxCCQ:           95,
+		TxRate:          "130Mbps",
+		RxRate:          "130Mbps",
+		Uptime:          "3d12h5m",
+		Distance:        150,
+		LastIP:          "192.168.1.100",
+		TxSignalStrength: -65,
+		Bytes:           "123456,789012",
+	}
+	if entry.Interface != "wlan1" {
+		t.Error("Interface field not set correctly")
+	}
+	if entry.MacAddress != "AA:BB:CC:DD:EE:FF" {
+		t.Error("MacAddress field not set correctly")
+	}
+	if entry.SignalStrength != -67 {
+		t.Error("SignalStrength field not set correctly")
+	}
+}