fix: reduce repeater web panel pressure and improve mqtt diagnostics

README.md

@@ -163,6 +163,8 @@ Features include:
 - light and dark themes
 - optional disable via `set web off`
 
+Recommended use is initial setup and occasional troubleshooting. On MQTT repeater deployments, disable the panel again when finished if you want maximum MQTT heap headroom.
+
 Some constrained targets disable the panel to stay within flash limits. For example, `Xiao_C3_repeater_mqtt` builds with `WITH_WEB_PANEL=0`.
 
 ### Companion WiFi Additions