fix: heartbeat only to SAC, never Telegram/email

agent.heartbeat bypasses NOTIFY_CHAIN in all UseSAC modes; SAC ingest only.
Bump to 1.2.3-SAC.

sac-client.sh

@@ -292,6 +292,10 @@ print(json.dumps(out) if out else "")
 PY
 }
 
+sac_is_heartbeat_only_event() {
+ [ "${1:-}" = "agent.heartbeat" ]
+}
+
 # notify_or_sac type severity title summary telegram_message [details_json]
 notify_or_sac() {
  local event_type="$1"
@@ -307,6 +311,22 @@ notify_or_sac() {
  local mode
  mode="$(sac_normalize_mode "${UseSAC:-off}")"
 
+ # Периодический heartbeat — только SAC (браузер), без Telegram/email в любом режиме.
+ if sac_is_heartbeat_only_event "$event_type"; then
+  case "$mode" in
+  off)
+   return 0
+   ;;
+  exclusive|dual|fallback)
+   sac_send_event "$event_type" "$severity" "$title" "$summary" "$details_json"
+   return $?
+   ;;
+  *)
+   return 0
+   ;;
+  esac
+ fi
+
  case "$mode" in
  off)
  notify_send "$telegram_message"