Replace the JS-built Leaflet control panel with a server-side
sidebar (desktop) and mobile floating controls. Band checkboxes,
callsign filter, and nav links now match the main propagation map
layout. Filter state managed by LiveView, pushed to JS via events.
- Callsign input filters contacts where either station matches
(case-insensitive substring match, debounced 300ms)
- Band checkboxes now show per-band count of visible contacts
- All/None buttons for quick band selection
- Header count updates dynamically with filters
- Complete rewrite: rebuilds map on any filter change instead of
toggling individual layers (simpler, handles cross-filter correctly)
- Leaflet map on contact detail pages showing both station locations
- SRTM elevation profile with Chart.js: terrain, LOS, Fresnel zone
- Path info: distance, azimuth, elevation angle in both directions
- Compact 4-column grid layout for contact details
- Contact map page with all contacts plotted
- Rename QSOs to Contacts in page header
- Wrap algo page in standard layout
