lightning add spacing between numeric and units

[MichaelWheeley]

What does this PR do?

• ref Nearby Lightning Strikes Panel #992
• adds space between numerical values and unit

Type of change

style

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)

[accius]

Clean style fix. One small nit: in useLightning.js around the new nearbyStrikes interpolation, there's now both an explicit space (} ${distStr}) and a leading space inside distStr itself (` (${PROXIMITY_RADIUS_KM} km)`), which gives a double space in the source. HTML collapses it on render so there's no visual issue — just an FYI for next time.

Otherwise +1, ready to merge.