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>

main/cmd/cmd_handler.c

@@ -58,6 +58,8 @@ static const char *message_type_name(uint16_t id) {
     return "TAP_NOTIFY";
   case alox_MessageType_TAP_SNAPSHOT:
     return "TAP_SNAPSHOT";
+  case alox_MessageType_CACHE_STATUS:
+    return "CACHE_STATUS";
   default:
     return "UNKNOWN";
   }