refactor(map): deduplicate hover/glow logic and extract timeout constant

[ceotjoe]

What does this PR do?

• Add POPUP_AUTO_CLOSE_MS = 20_000 module-level constant; replace the two inline 20000 literals in bindSpotClick
• Add bindHoverGlow(marker, latlng, color, markersRef) useCallback that owns all mouseover/mouseout popup + glow logic: uses a Leaflet glow ring for SVG circleMarkers (this._path) and a CSS drop-shadow filter for divIcon markers (this._icon), auto-detected at event time
• Replace ~150 lines of repeated inline mouseover/mouseout handlers across DX circles, DX labels, POTA/SOTA/WWFF/WWBOTA markers and labels, PSK Reporter TX+RX, and WSJT-X with a single bindHoverGlow() call each

Type of change

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

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