Refactor state imports and add MQTT regression test

[AndreasBeyer]

Summary

• update handler and paketbox to import the central state module instead of individual MQTT globals and add a reusable helper for publishing error states
• ensure all MQTT interactions now go through state.mqttObject/state.sendMqttErrorState
• add a regression test that verifies ResetErrorState clears the suppression flag so the next error publishes again

Testing

• python -m unittest tests.test_paketbox

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Codex Task