refactor(adsb): use MapUtils.init + tactical overlays on radar map

Replace custom createFallbackGridLayer/upgradeRadarTilesFromSettings with
MapUtils.init(), add range ring + reticle + HUD panel overlays via
MapUtils.addTacticalOverlays(), and wire updateCount/updateReticle into
the SSE aircraft handler and drawRangeRings.

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

tests/test_map_utils.py

@@ -17,3 +17,15 @@ def test_map_utils_css_is_served(client):
     assert resp.status_code == 200
     data = resp.data.decode()
     assert "map-hud-panel" in data
+
+
+def test_adsb_dashboard_includes_map_utils(client):
+    """ADS-B dashboard loads map-utils.js and map-utils.css."""
+    with client.session_transaction() as sess:
+        sess["logged_in"] = True
+    resp = client.get("/adsb/dashboard")
+    assert resp.status_code == 200
+    html = resp.data.decode()
+    assert "map-utils.js" in html
+    assert "map-utils.css" in html
+    assert "MapUtils.init" in html