fix: make planning board week start configurable

frontend/pages/organisation/plantafel.vue

@@ -184,12 +184,16 @@ const resolvedPlanningBoardConfig = computed(() => {
   const normalizedStartTime = /^\d{2}:\d{2}$/.test(String(config.startTime || "")) ? String(config.startTime) : "06:00"
   const normalizedEndTime = /^\d{2}:\d{2}$/.test(String(config.endTime || "")) ? String(config.endTime) : "21:00"
   const normalizedSlotMinutes = Number(config.slotMinutes)
+  const normalizedWeekStartsOn = Number(config.weekStartsOn)
   const allowedSlotMinutes = [15, 30, 60, 120, 180]
 
   return {
     startTime: normalizedStartTime,
     endTime: normalizedEndTime,
-    slotMinutes: allowedSlotMinutes.includes(normalizedSlotMinutes) ? normalizedSlotMinutes : 180
+    slotMinutes: allowedSlotMinutes.includes(normalizedSlotMinutes) ? normalizedSlotMinutes : 180,
+    weekStartsOn: Number.isInteger(normalizedWeekStartsOn) && normalizedWeekStartsOn >= 1 && normalizedWeekStartsOn <= 5
+      ? normalizedWeekStartsOn
+      : 1
   }
 })
 
@@ -295,6 +299,7 @@ const visibleDraftEventIds = computed(() =>
 const calendarOptions = computed(() => ({
   schedulerLicenseKey: "CC-Attribution-NonCommercial-NoDerivatives",
   locale: deLocale,
+  firstDay: resolvedPlanningBoardConfig.value.weekStartsOn,
   plugins: [resourceTimelinePlugin, interactionPlugin],
   initialView: calendarView.value,
   initialDate: calendarCurrentDate.value,
@@ -349,6 +354,7 @@ const calendarOptions = computed(() => ({
     resourceTimelineWeek: {
       type: "resourceTimeline",
       duration: { days: 7 },
+      dateAlignment: "week",
       buttonText: "Woche",
       slotDuration: { minutes: resolvedPlanningBoardConfig.value.slotMinutes },
       snapDuration: { minutes: resolvedPlanningBoardConfig.value.slotMinutes },