Firmware, MQTT Broker, HIVEMQ Testing

[ForrestErickson]

Is your feature request related to a problem? Please describe.
_A clear and concise description of what the problem is. Ex.

I'm always frustrated when our testing is only throught the shiftr.io brocker.

Describe the solution you'd like
A clear and concise description of what you want to happen.
We need to try other brokers.
Because @Yhya99 is testing the gateway with the HIVEMQ broker, we need to try the HIVEMQ public evaluation broker.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

We also should try the MOSQUITTO public broker.
We should install MOSQUITTO local brokers.

CC: @nk25719

[ForrestErickson]

Lee's MQTT Terminal Setup

Broker setup

Subscription topics:

[ForrestErickson]

Note on 20260322 Lee committed changes to main on the GPAD_API firmware, which allow compile time selection of the HIVEMQ broker instead of the default shiftrio MQTT broker.

From git log:

commit 07e79fc0200ffa6ccdbed88719d5472ec26ac1f3
Author: Forrest Erickson <forresterickson@comcast.net>
Date:   Sun Mar 22 11:57:18 2026 -0400

    PMD_Processing_MQTT.pde, Add MAC address for US0009.

commit 188b4623a270eae8c73e037b933aabc3b4265c1b
Author: Forrest Erickson <forresterickson@comcast.net>
Date:   Sun Mar 22 11:03:14 2026 -0400

    GPAD_API.ino, Make a #define to swith broker to HIVEMQ. COmment the MQTT port type.