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>

main/cmd/cmd_client_info.c

@@ -27,6 +27,7 @@ static bool encode_clients_list(pb_ostream_t *stream, const pb_field_t *field,
     proto.last_success_ping =
         client_registry_ms_since(client->last_success_ping_at);
     proto.version = client->version;
+    proto.accel_stream_enabled = client->accel_stream_enabled;
     proto.mac.funcs.encode = uart_cmd_encode_bytes;
     proto.mac.arg = &mac;