Add CACHE_STATUS UART poll and dashboard live stream.

Combine cached accel and tap in one low-overhead master command for ~16 ms
host polling. The dashboard uses a single live-stream toggle plus per-slave
accel-stream controls; fix live_stream state so polling is not cleared every
slow client refresh.

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

goTool/api_tap.go

@@ -38,13 +38,6 @@ type tapEventView struct {
 	AgeMs    uint32 `json:"age_ms"`
 }
 
-type tapReceiveAPIResponse struct {
-	ClientID uint32 `json:"client_id"`
-	Enabled  bool   `json:"enabled"`
-	Success  bool   `json:"success"`
-	Error    string `json:"error,omitempty"`
-}
-
 func mountTapAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl) {
 	mux.HandleFunc("GET /api/clients/{clientID}/tap-notify", func(w http.ResponseWriter, r *http.Request) {
 		clientID, err := parsePathClientID(r)
@@ -62,15 +55,6 @@ func mountTapAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, tapCtl *ta
 		}
 		serveClientTapNotifyPut(w, r, clientID, link, hub, tapCtl)
 	})
-	mux.HandleFunc("PUT /api/clients/{clientID}/tap-receive", func(w http.ResponseWriter, r *http.Request) {
-		clientID, err := parsePathClientID(r)
-		if err != nil {
-			writeJSON(w, http.StatusBadRequest, tapReceiveAPIResponse{Error: err.Error()})
-			return
-		}
-		serveClientTapReceivePut(w, r, clientID, hub)
-	})
-
 	mux.HandleFunc("/api/tap-notify", func(w http.ResponseWriter, r *http.Request) {
 		switch r.Method {
 		case http.MethodGet:
@@ -181,24 +165,6 @@ func serveTapNotifyPost(w http.ResponseWriter, r *http.Request, link *managedSer
 	writeJSON(w, status, out)
 }
 
-func serveClientTapReceivePut(w http.ResponseWriter, r *http.Request, clientID uint32, hub *wsHub) {
-	var body struct {
-		Enable bool `json:"enable"`
-	}
-	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
-		writeJSON(w, http.StatusBadRequest, tapReceiveAPIResponse{Error: "invalid JSON"})
-		return
-	}
-	if hub != nil {
-		hub.patchClientTapReceive(clientID, body.Enable)
-	}
-	writeJSON(w, http.StatusOK, tapReceiveAPIResponse{
-		ClientID: clientID,
-		Enabled:  body.Enable,
-		Success:  true,
-	})
-}
-
 func applyTapNotifyAll(link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl, single, doubleTap, triple bool) (uint32, error) {
 	resp, err := link.TapNotify(&pb.TapNotifyRequest{
 		Write:      true,