- 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
Rename all modules, functions, variables, routes, and UI text from
qso/qsos to contact/contacts. Database table stays as "qsos" to avoid
migration. Add /qsos -> /contacts redirects for old URLs.
