Add selectable ESP-NOW send path for accel/tap input.

Expose best_effort/fast/wait/reliable via UART, dashboard, and CLI so
loss vs latency can be compared under real multi-pod load.

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

main/proto/esp_now_messages.proto

@@ -31,6 +31,8 @@ enum EspNowMessageType {
   ESPNOW_ASSIGN_ID = 22;
   /** Master → slave: forget persisted master/id binding (debug reset). */
   ESPNOW_CLEAR_ID_BINDING = 23;
+  /** Master → slave: accel/tap ESP-NOW send path (best_effort/fast/wait/reliable). */
+  ESPNOW_SET_INPUT_SEND_MODE = 24;
 }
 
 message EspNowUnicastTest {
@@ -138,6 +140,15 @@ message EspNowTapEvent {
   uint32 kind = 2;
 }
 
+/**
+ * Master → slave: which esp_now_core_send_* path to use for ACCEL_SAMPLE / TAP_EVENT.
+ * Values match uart InputSendMode (0=best_effort … 3=reliable).
+ */
+message EspNowInputSendMode {
+  uint32 client_id = 1; // 0 = all slaves; otherwise only matching slave_id applies
+  uint32 mode = 2;
+}
+
 /** Slave → master: LiPo voltages (periodic ~30 s and on query). */
 message EspNowBatteryReport {
   uint32 client_id = 1;
@@ -208,5 +219,6 @@ message EspNowMessage {
     EspNowTapConfig tap_config = 22;
     EspNowAssignId assign_id = 23;
     EspNowClearIdBinding clear_id_binding = 24;
+    EspNowInputSendMode input_send_mode = 25;
   }
 }