fix: sweep final hardcoded cyan from mode JS files and CSS

- proximity-radar.js: fix missed dot stroke in new-device creation path
- gps.js: GPS constellation color via object getter; globe atmosphere reads CSS var
- websdr.js: globe atmosphere, map markers, popup buttons, point label use CSS var
- subghz.js: canvas strokeStyle reads --accent-cyan
- sstv.js: ISS track polyline reads --accent-cyan
- app.js: info message border-left uses var(--accent-cyan)
- subghz.css, gps.css: replace all #00d4ff with var(--accent-cyan)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/js/modes/sstv.js

@@ -254,14 +254,14 @@ const SSTV = (function() {
 
         // Past track (dimmer, solid)
         issTrackPast = L.polyline([], {
-            color: '#00d4ff',
+            color: getComputedStyle(document.documentElement).getPropertyValue('--accent-cyan').trim() || '#00d4ff',
             weight: 1.5,
             opacity: 0.3,
         }).addTo(issMap);
 
         // Future track (brighter, dashed)
         issTrackLine = L.polyline([], {
-            color: '#00d4ff',
+            color: getComputedStyle(document.documentElement).getPropertyValue('--accent-cyan').trim() || '#00d4ff',
             weight: 2,
             opacity: 0.7,
             dashArray: '6, 4'