[BUG 695] Lightning layer is not using settable distance units

[alanhargreaves]

What does this PR do?

Updated to use the global allUnits.dist for 'metric' vs 'imperlal' for distance display.

All comparisons are still done in km, but we display in the appropriate unit.

I also had to update the panel header to list the strike radius in both units, in order to have this fit, i had to override the font size down to 11px.

Addresses #695

Type of change

• Bug fix
• New feature
• Performance improvement
• Refactor / code cleanup
• Documentation
• Translation
• Map layer plugin

How to test

1. Set distance units to Imperial in the settings
2. Bring up the lightning layer (hotkey 'L')
3. Verify distances are listed in miles

Checklist

• App loads without console errors
• Tested in Dark, Light, and Retro themes
• Responsive at different screen sizes (desktop + mobile)
• If touching server.js: caches have TTLs and size caps (we serve 2,000+ concurrent users)
• If adding an API route: includes caching and error handling
• If adding a panel: wired into Modern, Classic, and Dockable layouts
• No hardcoded colors — uses CSS variables (var(--accent-cyan), etc.)
• No .bak, .old, console.log debug lines, or test scripts included

Screenshots (if visual change)

Before:

After:

[accius]

Approve with minor fixes. Good change overall, distances now respect unit preferences cleanly.

Three small things:

Line 835 still passes 'km' to calculateDistance which no longer accepts a unit parameter. Silently ignored but it's dead code:

// current
const distance = calculateDistance(stationLat, stationLon, strike.lat, strike.lon, 'km');
// should be
const distance = calculateDistance(stationLat, stationLon, strike.lat, strike.lon);

The nearby strikes header crams both units in and shrinks the font to compensate. Since allUnits is right there, just show the user's preference:

// current
`📍 Nearby Strikes(30km/18.6miles)`
// cleaner
`📍 Nearby Strikes (${allUnits.dist === 'metric' ? '30 km' : '18.6 mi'})`

Same applies to the "No strikes within 30km (18.6 miles)" string further down. Also missing a space before the parenthesis in Strikes(30km.

[alanhargreaves]

I tried that. It doesn't work as it's only evaluated when the Panel is created. If you change units, it doesn't change with you.