feat: restructure flow to date-first and add support for long/short days and activities

checkout.js

@@ -31,16 +31,25 @@
   });
   summaryDate.textContent = formattedDate;
 
-  // Icon aus appsettings.json laden, falls verfügbar
-  fetch("appsettings.json")
-    .then((res) => res.json())
-    .then((settings) => {
-      const match = (settings.activities || []).find((a) => a.name === selectedActivity);
-      if (match && match.icon) {
-        activityIcon.textContent = match.icon;
-      }
-    })
-    .catch(() => {});
+  // Icons aus selectedActivities oder appsettings.json laden
+  let storedActivities = [];
+  try {
+    storedActivities = JSON.parse(localStorage.getItem("selectedActivities") || "[]");
+  } catch (e) {}
+
+  if (storedActivities.length > 0) {
+    activityIcon.textContent = storedActivities.map((a) => a.icon).join(" ");
+  } else {
+    fetch("appsettings.json")
+      .then((res) => res.json())
+      .then((settings) => {
+        const match = (settings.activities || []).find((a) => a.name === selectedActivity);
+        if (match && match.icon) {
+          activityIcon.textContent = match.icon;
+        }
+      })
+      .catch(() => {});
+  }
 
   checkoutBtn.addEventListener("click", () => {
     // Später: API / Mail-Versand / Kalendereintrag ausführen