FR: Make the HTML dashboard more automated

[uurf]

1. can it load ~/Developer/ml_toolkit/asset_serial_list.csv automatically and ask for a CSV if it can't be found?
2. could any of the relevant scripts like ml_scan.sh and ml_deploy.sh connect and ml_status.sh --json > status/latest.json be fired by controls on the dashboard?
3. can ml_deploy.sh reboot and ml_deploy.sh shutdown be fired from controls on the dashboard?

[uurf]

scoped in /docs/dashboard_controls_proposal.md