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/powerpod.c

@@ -1,7 +1,8 @@
 #include "app_config.h"
 #include "cmd_handler.h"
 #include "cmd_accel_deadzone.h"
-#include "cmd_accel_read.h"
+#include "cmd_accel_snapshot.h"
+#include "cmd_accel_stream.h"
 #include "cmd_espnow_unicast_test.h"
 #include "cmd_espnow_find_me.h"
 #include "cmd_restart.h"
@@ -178,7 +179,8 @@ void app_main(void) {
     cmd_version_register();
     cmd_client_info_register();
     cmd_accel_deadzone_register();
-    cmd_accel_read_register();
+    cmd_accel_snapshot_register();
+    cmd_accel_stream_register();
     cmd_espnow_unicast_test_register();
     cmd_espnow_find_me_register();
     cmd_restart_register();