fix: generate web panel certs per build and clean up mqtt env flags

platformio.ini

@@ -58,7 +58,9 @@ build_src_filter =
 extends = arduino_base
 platform = platformio/espressif32@6.11.0
 monitor_filters = esp32_exception_decoder
-extra_scripts = merge-bin.py
+extra_scripts =
+  pre:arch/esp32/extra_scripts/generate_web_panel_cert.py
+  merge-bin.py
 build_flags = ${arduino_base.build_flags}
   -D ESP32_PLATFORM
 ;  -D ESP32_CPU_FREQ=80          ; change it to your need