Add RESTART command for master and slaves via ESP-NOW.

UART RESTART (client_id 0 = local reboot, >0 = unicast); dashboard and CLI hooks; delayed esp_restart after response.

Co-authored-by: Cursor <cursoragent@cursor.com>

goTool/api_serve.go

@@ -50,6 +50,16 @@ type findMeAPIResponse struct {
 	Error    string `json:"error,omitempty"`
 }
 
+type restartAPIRequest struct {
+	ClientID uint32 `json:"client_id"`
+}
+
+type restartAPIResponse struct {
+	Success  bool   `json:"success"`
+	ClientID uint32 `json:"client_id,omitempty"`
+	Error    string `json:"error,omitempty"`
+}
+
 type otaAPIResponse struct {
 	Success       bool   `json:"success"`
 	BytesWritten  uint32 `json:"bytes_written,omitempty"`
@@ -82,6 +92,13 @@ func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
 		}
 		serveFindMe(w, r, link)
 	})
+	mux.HandleFunc("/api/restart", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		serveRestart(w, r, link)
+	})
 	mux.HandleFunc("/api/ota", func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
 			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
@@ -233,6 +250,22 @@ func applyDeadzoneToSlaves(link *managedSerial, deadzone uint32) (uint32, error)
 	return updated, nil
 }
 
+func serveRestart(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	var body restartAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, restartAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	if err := link.Restart(body.ClientID); err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, restartAPIResponse{
+			ClientID: body.ClientID,
+			Error:    err.Error(),
+		})
+		return
+	}
+	writeJSON(w, http.StatusOK, restartAPIResponse{Success: true, ClientID: body.ClientID})
+}
+
 func serveFindMe(w http.ResponseWriter, r *http.Request, link *managedSerial) {
 	var body findMeAPIRequest
 	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {