- Add hardware/config fields migration to beacon_monitors table
- Update BeaconMonitor schema with provision/config changesets
- Add context functions: create_hardware, update_config, list_all_monitors
- Remove user-facing monitor creation (browser POST + API POST)
- Update settings page: show assigned monitors table with hardware info
- Update profile page: show assigned monitors, remove register links
- Fix all tests to match new API
Users can now register beacon monitors on the settings page. Each
monitor gets a unique random token the remote program will use to
authenticate its reports. Name is the only user-supplied field for
now; more will be added as the monitor protocol is defined.
Also adds :gen_smtp to deps. Swoosh's SMTP adapter depends on
:mimemail which lives in that package, and production was 500'ing
when trying to send confirmation emails without it.