Update InputClientSample struct to make TapKind optional and improve WebSocket API documentation. Adjust README to reflect changes in input push stream format and clarify connection flow. Enhance API_WEBSOCKET.md with detailed command and push message descriptions.

goTool/api_stream.go

@@ -31,7 +31,7 @@ type InputClientSample struct {
 	Y          int32  `json:"y,omitempty"`
 	Z          int32  `json:"z,omitempty"`
 	AccelAgeMs uint32 `json:"accel_age_ms,omitempty"`
-	TapKind    string `json:"tap_kind"`
+	TapKind    string `json:"tap_kind,omitempty"`
 	TapAgeMs   uint32 `json:"tap_age_ms,omitempty"`
 }
 
@@ -389,7 +389,6 @@ func (h *accelStreamHub) inputClientsFromCacheLocked(cache *pb.CacheStatusRespon
 	for _, c := range cache.GetClients() {
 		sample := InputClientSample{
 			ClientID: c.GetClientId(),
-			TapKind:  "none",
 		}
 		if a := c.GetAccel(); a != nil {
 			sample.Valid = a.GetValid()