Dim LED ring, add blink mode, and signal OTA outcome on the ring.

Default brightness is ~5%; UART blink mode and green/red pulses mark OTA success or failure. Failed UART uploads skip ESP-NOW distribution.

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

main/ota_uart.h

@@ -46,6 +46,12 @@ ota_feed_result_t ota_uart_feed(const uint8_t *data, size_t len);
 
 uint32_t ota_uart_bytes_written(void);
 
+/** Bytes accepted in the current session (includes buffered block). */
+uint32_t ota_uart_bytes_received(void);
+
+/** Image size from OTA_START / ESP-NOW OTA_START; 0 if inactive. */
+uint32_t ota_uart_total_size(void);
+
 /**
  * Flush remainder and esp_ota_end. When set_boot is false, the staged image
  * remains readable via ota_uart_get_staged_image() until ota_uart_apply_boot().