Added UI with station cards, grouping and styling

src/lib/api.js

@@ -0,0 +1,19 @@
+export async function fetchStations() {
+  const res = await fetch('/api/campagne_map_data');
+  if (!res.ok) throw new Error(`Errore HTTP ${res.status}`);
+  const geojson = await res.json();
+  return geojson.features
+    .map(f => ({ ...f.properties, pk: parseInt(f.properties.pk, 10) }))
+    .sort((a, b) => b.pk - a.pk);
+}
+
+export async function fetchDay(id, date) {
+  try {
+    const res = await fetch(`/api/get_measurements/${id}?day=${date}`);
+    if (!res.ok) return [];
+    const data = await res.json();
+    return data.misure ?? [];
+  } catch {
+    return [];
+  }
+}