Beacons:
- Scaffolded with phx.gen.live then reworked so reads are public
and mutations go through a live_session gated by the new
:require_admin on_mount hook in UserAuth
- Beacon schema stores frequency (MHz), callsign, grid, lat/lon,
power (W), and height above ground (m); grid auto-derives from
lat/lon when left blank via Maidenhead.from_latlon
- Adds Maidenhead.from_latlon/3 so we can compute grids locally
instead of hitting an external API
Users admin page:
- /users and /users/:id/edit (admin-only) for listing, editing
(callsign/name/email/is_admin), and deleting other users
- Adds Accounts.list_users, admin_update_user, delete_user, and
a dedicated admin_changeset on the User schema
- Nav gains a "Users" link for admins and a "Beacons" link for
everyone
Extend grid validation and decoding from 4/6 chars to unlimited
even-length grids (8, 10, etc). Recursive decoder handles alternating
letter(/24) and digit(/10) subdivision pairs after the field+square.
Validated against gridmap-web's Maidenhead implementation.
Maidenhead grid module converts grid squares to lat/lon coordinates.
Submission form validates grids, bands, modes, and email, computes
positions and distance, then triggers the weather/HRRR/terrain
processing pipeline via Oban.
