broke up the mega monolith that is the calendar file

ui/src/composables/useCalendarNavigation.ts

@@ -0,0 +1,33 @@
+import { ref } from "vue";
+
+export function useCalendarNavigation(calendarApiGetter: () => any) {
+    const selectedMonth = ref(new Date().getMonth());
+    const selectedYear = ref(new Date().getFullYear());
+
+    const years = Array.from({ length: 41 }, (_, i) => selectedYear.value - 20 + i);
+
+    function goPrev() { calendarApiGetter()?.prev(); }
+    function goNext() { calendarApiGetter()?.next(); }
+    function goToday() { calendarApiGetter()?.today(); }
+
+    function onDatesSet() {
+        const d = calendarApiGetter()?.getDate() ?? new Date();
+        selectedMonth.value = d.getMonth();
+        selectedYear.value = d.getFullYear();
+    }
+
+    function goToSelectedDate() {
+        calendarApiGetter()?.gotoDate(new Date(selectedYear.value, selectedMonth.value, 1));
+    }
+
+    return {
+        selectedMonth,
+        selectedYear,
+        years,
+        goPrev,
+        goNext,
+        goToday,
+        onDatesSet,
+        goToSelectedDate,
+    };
+}