feat: Make trails checked by default and remove both radar modes from ADS-B

Trails checkbox now defaults to checked (on). Removed the RADAR view
toggle, Radar overlay checkbox, RadarScope class, and all associated
animation/overlay JS and CSS.

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

static/css/adsb_dashboard.css

@@ -872,42 +872,6 @@ body {
     display: block;
 }
 
-#radarOverlayCanvas {
-    position: absolute;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-    pointer-events: none;
-    z-index: 500;
-    display: none;
-}
-
-#radarOverlayCanvas.active {
-    display: block;
-}
-
-#radarScope {
-    position: absolute;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-    display: none;
-    background: var(--radar-bg);
-}
-
-#radarScope.active {
-    display: flex;
-    justify-content: center;
-    align-items: center;
-}
-
-#radarCanvas {
-    max-width: 100%;
-    max-height: 100%;
-}
-
 /* Right sidebar - Mobile first */
 .sidebar {
     display: flex;
@@ -934,42 +898,6 @@ body {
     }
 }
 
-/* View toggle */
-.view-toggle {
-    display: flex;
-    padding: 10px;
-    gap: 8px;
-    background: var(--bg-panel);
-    border-bottom: 1px solid rgba(74, 158, 255, 0.2);
-}
-
-.view-btn {
-    flex: 1;
-    padding: 10px;
-    border: 1px solid rgba(74, 158, 255, 0.3);
-    background: transparent;
-    color: var(--text-secondary);
-    font-family: 'Orbitron', monospace;
-    font-size: 11px;
-    font-weight: 600;
-    text-transform: uppercase;
-    letter-spacing: 2px;
-    border-radius: 4px;
-    cursor: pointer;
-    transition: all 0.2s ease;
-}
-
-.view-btn:hover {
-    border-color: var(--accent-cyan);
-    color: var(--accent-cyan);
-}
-
-.view-btn.active {
-    background: var(--accent-cyan);
-    border-color: var(--accent-cyan);
-    color: var(--bg-dark);
-}
-
 /* Selected aircraft panel */
 .selected-aircraft {
     flex-shrink: 0;