os: Move /home/pi/PlanktoScope to /opt

[sonnyp]

Follow up:

• os: Implement A/B partitions #919
• os: Use RAUC for updates #935

for #923

/home/pi is on a partition "DATA" that is shared between ROOT A and ROOT B
PlanktoScope is part of the OS so it should be on the ROOT partitions and not shared

hardware.json, config.json and calibraton.json did not change path for now as we need to figure out the upgrade story

Migrate

cd /home/pi/PlanktoScope
git checkout main
git pull
sudo mv /home/pi/PlanktoScope /opt
sudo chown -R pi:pi /opt/PlanktoScope
mkdir /home/pi/PlanktoScope
mv /opt/PlanktoScope/config.json /home/pi/PlanktoScope
mv /opt/PlanktoScope/hardware.json /home/pi/PlanktoScope
mv /opt/PlanktoScope/calibration.json /home/pi/PlanktoScope
cd /opt/PlanktoScope/documentation
uv venv
cd /opt/PlanktoScope
just