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/host_transport.c

@@ -22,14 +22,14 @@ void host_transport_set_cmd_queue(QueueHandle_t cmd_queue) {
 
 QueueHandle_t host_transport_cmd_queue(void) { return s_cmd_queue; }
 
-bool host_enqueue_packet(const uint8_t *payload, uint8_t len) {
+bool host_enqueue_packet(const uint8_t *payload, size_t len) {
   if (s_cmd_queue == NULL || payload == NULL || len == 0) {
     return false;
   }
 
   generic_msg_t msg = {
       .msg_id = payload[0],
-      .len = len > 1 ? (size_t)(len - 1) : 0,
+      .len = len > 1 ? (len - 1) : 0,
       .payload = NULL,
   };
 
@@ -63,10 +63,11 @@ esp_err_t host_send_framed(const uint8_t *payload, size_t len) {
     checksum ^= payload[i];
   }
 
-  uint8_t frame[4 + MAX_PAYLOAD_SIZE];
+  uint8_t frame[UART_FRAME_OVERHEAD + MAX_PAYLOAD_SIZE];
   size_t pos = 0;
   frame[pos++] = START_MARKER;
-  frame[pos++] = (uint8_t)len;
+  frame[pos++] = (uint8_t)(len & 0xff);
+  frame[pos++] = (uint8_t)((len >> 8) & 0xff);
   memcpy(&frame[pos], payload, len);
   pos += len;
   frame[pos++] = checksum;