Raise host frame payload limit so multi-client UART replies fit.

Use a uint16 LE length and 1024-byte max payload so CLIENT_INFO and BATTERY_STATUS no longer fail encoding past ~10 connected pods.

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

main/uart.c

@@ -81,18 +81,27 @@ bool parse_uart_byte(uint8_t byte, uart_packet_t *p) {
     if (byte == START_MARKER) {
       p->index = 0;
       p->checksum = 0;
-      p->state = STATE_LEN;
+      p->len = 0;
+      p->state = STATE_LEN_LO;
     }
     break;
 
-  case STATE_LEN:
-    if (byte > MAX_PAYLOAD_SIZE || byte == 0) {
+  case STATE_LEN_LO:
+    p->len = byte;
+    p->state = STATE_LEN_HI;
+    break;
+
+  case STATE_LEN_HI: {
+    uint16_t len = (uint16_t)(p->len | ((uint16_t)byte << 8));
+    if (len == 0 || len > MAX_PAYLOAD_SIZE) {
       p->state = STATE_START;
     } else {
-      p->len = byte;
+      p->len = len;
+      p->index = 0;
       p->state = STATE_DATA;
     }
     break;
+  }
 
   case STATE_DATA:
     p->payload[p->index++] = byte;