use empty placeholder cells for weekdays that are not part of the shown month

web/src/lib/event.ts

@@ -168,20 +168,20 @@ export function organizeEventsInCalendar(
 
   let currentDate = startOfWeek(minDate, { weekStartsOn: 1 });
   while (currentDate <= maxDate) {
-    const yearMonth = formatDate(currentDate, "yyyy-MM");
     const week = formatDate(currentDate, "w");
     const daysOfWeek = eachDayOfInterval({
       start: currentDate,
       end: endOfWeek(currentDate, { weekStartsOn: 1 }),
     });
 
-    if (!calendar[yearMonth]) {
-      calendar[yearMonth] = {};
-    }
-    if (!calendar[yearMonth][week]) {
-      calendar[yearMonth][week] = {};
-    }
     daysOfWeek.forEach((day) => {
+      const yearMonth = formatDate(day, "yyyy-MM");
+      if (!calendar[yearMonth]) {
+        calendar[yearMonth] = {};
+      }
+      if (!calendar[yearMonth][week]) {
+        calendar[yearMonth][week] = {};
+      }
       const formattedDay = formatDate(day, "yyyy-MM-dd");
       if (!calendar[yearMonth][week][formattedDay]) {
         calendar[yearMonth][week][formattedDay] = [];