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/proto/uart_messages.proto

@@ -110,8 +110,8 @@ message EspNowUnicastTestResponse {
   uint32 seq = 2;
 }
 
-// Host → device: LED ring display (progress bar, digit, or clear).
-// mode: 0=clear, 1=progress (0–100 %), 2=digit (0–10, same layout as firmware digit maps).
+// Host → device: LED ring display (progress bar, digit, clear, or blink).
+// mode: 0=clear, 1=progress (0–100 %), 2=digit (0–10), 3=blink full ring.
 message LedRingProgressRequest {
   uint32 mode = 1;
   /** 0–100: fraction of ring LEDs to light (mode=progress) */
@@ -121,8 +121,12 @@ message LedRingProgressRequest {
   uint32 r = 4;
   uint32 g = 5;
   uint32 b = 6;
-  /** 0–255 brightness scale applied to r/g/b */
+  /** 0–255 brightness scale; 0 = firmware default (~5 %) */
   uint32 intensity = 7;
+  /** Pulse length in ms (mode=blink, default 350) */
+  uint32 blink_ms = 8;
+  /** Number of pulses (mode=blink, default 1) */
+  uint32 blink_count = 9;
 }
 
 message LedRingProgressResponse {