Stream slave accel via ESP-NOW with master snapshot cache.

Slaves push BMA456 samples at 16ms when enabled; the master caches per
client and exposes ACCEL_SNAPSHOT and ACCEL_STREAM over UART. goTool adds
dashboard stream controls, HTTP accel-stream routes, and an external
WebSocket API with per-connection receive/interval and slave stream commands.

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

goTool/api_serve.go

@@ -67,7 +67,8 @@ type otaAPIResponse struct {
 	Error         string `json:"error,omitempty"`
 }
 
-func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
+func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, streamCtl *accelStreamCtl) {
+	mountAccelStreamAPI(mux, link, hub, streamCtl)
 	mux.HandleFunc("/api/deadzone", func(w http.ResponseWriter, r *http.Request) {
 		switch r.Method {
 		case http.MethodGet: