feat(snmp,ui): устройства за портом (MAC/IP) в таблице 2

Добавил сбор FDB/ARP по SNMP (BRIDGE-MIB + ipNetToMedia), хранение и API /port-devices.
В UI Таблица 2 теперь показывает MAC/IP за выбранным портом после клика по строке Таблицы 1.

Made-with: Cursor

internal/api/handler.go

@@ -69,6 +69,7 @@ func (h *Handler) Routes() http.Handler {
 	mux.HandleFunc("GET /api/scans/{id}/snmp", h.getScanSNMP)
 	mux.HandleFunc("GET /api/scans/{id}/lldp", h.getScanLLDP)
 	mux.HandleFunc("GET /api/scans/{id}/interfaces", h.getScanInterfaces)
+	mux.HandleFunc("GET /api/scans/{id}/port-devices", h.getScanPortDevices)
 	mux.HandleFunc("GET /api/scans/{id}/links", h.getScanLinks)
 	mux.HandleFunc("GET /api/scans/{id}/topology", h.getScanTopology)
 	mux.HandleFunc("POST /api/admin/purge-scans", h.postAdminPurgeScans)
@@ -330,6 +331,44 @@ func (h *Handler) getScanInterfaces(w http.ResponseWriter, r *http.Request) {
 	})
 }
 
+func (h *Handler) getScanPortDevices(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	if id == "" {
+		writeError(w, http.StatusBadRequest, "scan id is required")
+		return
+	}
+	if _, ok := h.store.GetScan(id); !ok {
+		writeError(w, http.StatusNotFound, "scan not found")
+		return
+	}
+	ip := strings.TrimSpace(r.URL.Query().Get("ip"))
+	if ip == "" {
+		writeError(w, http.StatusBadRequest, "query parameter ip is required")
+		return
+	}
+	ifIndex := 0
+	if raw := strings.TrimSpace(r.URL.Query().Get("if_index")); raw != "" {
+		n, err := strconv.Atoi(raw)
+		if err != nil || n < 0 {
+			writeError(w, http.StatusBadRequest, "if_index must be >= 0")
+			return
+		}
+		ifIndex = n
+	}
+	limit := 20000
+	if raw := r.URL.Query().Get("limit"); raw != "" {
+		n, err := strconv.Atoi(raw)
+		if err != nil || n <= 0 || n > 100000 {
+			writeError(w, http.StatusBadRequest, "limit must be between 1 and 100000")
+			return
+		}
+		limit = n
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"items": h.store.ListPortDeviceResults(id, ip, ifIndex, limit),
+	})
+}
+
 func (h *Handler) getScanLinks(w http.ResponseWriter, r *http.Request) {
 	id := r.PathValue("id")
 	if id == "" {