[style](trx-frontend): theme radio path line via CSS var

Remove hardcoded #3388ff colour from L.polyline options; use
stroke: var(--accent-green) and stroke-opacity in the CSS class
so the path follows the active colour scheme automatically.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -2436,7 +2436,7 @@ function initAprsMap() {
     if (serverLat != null && serverLon != null) {
       aprsRadioPath = L.polyline(
         [[serverLat, serverLon], [ll.lat, ll.lng]],
-        { className: "aprs-radio-path", color: "#3388ff", weight: 2, opacity: 0.85, interactive: false }
+        { className: "aprs-radio-path", weight: 2, interactive: false }
       ).addTo(aprsMap);
     }
   });