style(portal): overview map uses dot markers, matching the internal project map

Swap Leaflet's default teardrop pins for L.circleMarker (radius 8, seismo-orange
fill, white border) + a name tooltip, same as partials/projects/location_map.html.
Also disables scroll-wheel zoom to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

templates/portal/overview.html

@@ -81,14 +81,18 @@ const withCoords = LOCATIONS.filter(l => l.coordinates);
 if (withCoords.length) {
     const mapEl = document.getElementById('loc-map');
     mapEl.classList.remove('hidden');
-    const map = L.map('loc-map');
+    const map = L.map('loc-map', { scrollWheelZoom: false });
     L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
         { maxZoom: 19, attribution: '© OpenStreetMap' }).addTo(map);
     const pts = [];
     withCoords.forEach(l => {
         const [la, lo] = (l.coordinates || '').split(',').map(Number);
         if (!isNaN(la) && !isNaN(lo)) {
-            L.marker([la, lo]).addTo(map).bindPopup(l.name);
+            // Same dot style as the internal project map (circleMarker, not a pin).
+            L.circleMarker([la, lo], {
+                radius: 8, fillColor: '#f48b1c', color: '#fff',
+                weight: 2, opacity: 1, fillOpacity: 0.9,
+            }).addTo(map).bindTooltip(l.name, { direction: 'top', offset: [0, -6] });
             pts.push([la, lo]);
         }
     });