[style](trx-frontend): theme receiver marker via CSS var

Remove hardcoded #3388ff from the TRX circleMarker; apply
.trx-receiver-marker class and use stroke/fill: var(--accent-green)
so the dot follows the active colour scheme.

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

@@ -2447,7 +2447,7 @@ function initAprsMap() {
 
   if (hasLocation) {
     aprsMapReceiverMarker = L.circleMarker([serverLat, serverLon], {
-      radius: 8, color: "#3388ff", fillColor: "#3388ff", fillOpacity: 0.8
+      radius: 8, className: "trx-receiver-marker", fillOpacity: 0.8
     }).addTo(aprsMap).bindPopup("");
   }
 

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -1083,6 +1083,7 @@ small { color: var(--text-muted); }
 .aprs-popup-label { color: var(--text-muted); white-space: nowrap; padding-right: 0.5rem !important; }
 .aprs-popup-info { font-size: 0.85em; color: var(--text); border-top: 1px solid var(--border-light); padding-top: 0.25rem; margin-top: 0.1rem; word-break: break-word; }
 .aprs-radio-path { stroke: var(--accent-green) !important; stroke-opacity: 0.8 !important; stroke-dasharray: 10 5 !important; animation: aprs-radio-path-flow 0.7s linear infinite; }
+.trx-receiver-marker { stroke: var(--accent-green) !important; fill: var(--accent-green) !important; }
 .receiver-popup-active { font-size: 0.75em; background: rgba(194,75,26,0.15); color: var(--accent-green); border: 1px solid rgba(194,75,26,0.3); border-radius: 3px; padding: 0 0.25rem; margin-left: 0.3rem; vertical-align: middle; }
 @keyframes aprs-radio-path-flow { to { stroke-dashoffset: -15; } }
 .aprs-bar-pos { background: none; border: none; padding: 0; margin-left: 0.4em; font-family: inherit; font-size: inherit; color: var(--accent-green); cursor: pointer; }