Feature - Add support for a fiscal year period defined in user settings.

* Add "This fiscal year", "Last fiscal year" as date range options in Transaction Details to filter transactions to those periods
* Add fiscal year ranges to Statistics & Trend Analysis
* Add "fiscal year start date" to user profile settings, allowing the user to select any date of the calendar year as the start of the fiscal year
* Add "fiscal year format" to user profile settings, allowing the user to specify how financial year date labels should appear

Implementation notes:
* The default fiscal year start is January 1 and the default fiscal year display format is "FY 2025"
* Fiscal year start date (month number & day number) are stored together in db as a uint16, high byte & low byte respectively
* February 29 is disallowed as a fiscal year start date, since it is never used as a convention in any country
* Jest is added to the project as a dev dependency, for unit tests in frontend

Signed-off-by: Sebastian Reategui <seb.reategui@gmail.com>

src/components/desktop/FiscalYearStartSelect.vue

@@ -0,0 +1,96 @@
+<template>
+    <v-select
+        persistent-placeholder
+        :readonly="readonly"
+        :disabled="disabled"
+        :clearable="modelValue ? clearable : false"
+        :label="label"
+        :menu-props="{ contentClass: 'fiscal-year-start-select-menu' }"
+        v-model="selectedDate"
+    >
+        <template #selection>
+            <span class="text-truncate cursor-pointer">{{ displayName }}</span>
+        </template>
+
+        <template #no-data>
+            <vue-date-picker inline vertical auto-apply hide-offset-dates disable-year-select
+                             ref="datepicker"
+                             month-name-format="long"
+                             model-type="MM-dd"
+                             :clearable="false"
+                             :enable-time-picker="false"
+                             :dark="isDarkMode"
+                             :week-start="firstDayOfWeek"
+                             :day-names="dayNames"
+                             :disabled-dates="disabledDates"
+                             :start-date="selectedDate"
+                             v-model="selectedDate"
+                             >
+                <template #month="{ text }">
+                    {{ getMonthShortName(text) }}
+                </template>
+                <template #month-overlay-value="{ text }">
+                    {{ getMonthShortName(text) }}
+                </template>
+            </vue-date-picker>
+        </template>
+    </v-select>
+</template>
+
+<script setup lang="ts">
+import { computed } from 'vue';
+import { useTheme } from 'vuetify';
+import { useUserStore } from '@/stores/user.ts';
+import { ThemeType } from '@/core/theme.ts';
+import { arrangeArrayWithNewStartIndex } from '@/lib/common.ts';
+import {
+    type FiscalYearStartSelectionBaseProps,
+    type FiscalYearStartSelectionBaseEmits,
+    useFiscalYearStartSelectionBase
+} from '@/components/base/FiscalYearStartSelectionBase.ts';
+import { useI18n } from '@/locales/helpers.ts';
+
+interface FiscalYearStartSelectProps extends FiscalYearStartSelectionBaseProps {
+    disabled?: boolean;
+    readonly?: boolean;
+    clearable?: boolean;
+    label?: string;
+}
+
+const props = defineProps<FiscalYearStartSelectProps>();
+const emit = defineEmits<FiscalYearStartSelectionBaseEmits>();
+
+const { getMonthShortName } = useI18n();
+const theme = useTheme();
+
+const isDarkMode = computed<boolean>(() => theme.global.name.value === ThemeType.Dark);
+
+// Get all base functionality
+const {
+    dayNames,
+    displayName,
+    disabledDates,
+    firstDayOfWeek,
+    getModelValueToDateString,
+    getDateStringToModelValue,
+} = useFiscalYearStartSelectionBase(props, emit);
+
+const selectedDate = computed<string>({
+    get: () => {
+        return getModelValueToDateString();
+    },
+    set: (value: string) => {
+        emit('update:modelValue', getDateStringToModelValue(value));
+    }
+});
+</script>
+
+<style>
+.fiscal-year-start-select-menu {
+    max-height: inherit !important;
+}
+
+.fiscal-year-start-select-menu .dp__menu {
+    border: 0;
+}
+</style>

src/components/desktop/TrendsChart.vue

@@ -28,7 +28,8 @@ import {
 import {
     getYearMonthFirstUnixTime,
     getYearMonthLastUnixTime,
-    getDateTypeByDateRange
+    getDateTypeByDateRange,
+    getFiscalYearFromUnixTime
 } from '@/lib/datetime.ts';
 import {
     sortStatisticsItems
@@ -69,7 +70,7 @@ const emit = defineEmits<{
 }>();
 
 const theme = useTheme();
-const { tt, formatUnixTimeToShortYear, formatYearQuarter, formatUnixTimeToShortYearMonth, formatAmountWithCurrency } = useI18n();
+const { tt, formatUnixTimeToShortYear, formatYearQuarter, formatUnixTimeToShortYearMonth, formatUnixTimeToFiscalYear, formatYearToFiscalYear, formatAmountWithCurrency } = useI18n();
 const { allDateRanges, getItemName, getColor } = useTrendsChartBase(props);
 
 const userStore = useUserStore();
@@ -121,6 +122,8 @@ const allDisplayDateRanges = computed<string[]>(() => {
 
         if (props.dateAggregationType === ChartDateAggregationType.Year.type) {
             allDisplayDateRanges.push(formatUnixTimeToShortYear(dateRange.minUnixTime));
+        } else if (props.dateAggregationType === ChartDateAggregationType.FiscalYear.type && 'year' in dateRange) {
+            allDisplayDateRanges.push(formatUnixTimeToFiscalYear(dateRange.minUnixTime));
         } else if (props.dateAggregationType === ChartDateAggregationType.Quarter.type && 'quarter' in dateRange) {
             allDisplayDateRanges.push(formatYearQuarter(dateRange.year, dateRange.quarter));
         } else { // if (props.dateAggregationType === ChartDateAggregationType.Month.type) {
@@ -150,6 +153,12 @@ const allSeries = computed<TrendsChartDataItem[]>(() => {
 
             if (props.dateAggregationType === ChartDateAggregationType.Year.type) {
                 dateRangeKey = dataItem.year.toString();
+            } else if (props.dateAggregationType === ChartDateAggregationType.FiscalYear.type) {
+                const fiscalYear = getFiscalYearFromUnixTime(
+                    getYearMonthFirstUnixTime({ year: dataItem.year, month: dataItem.month }),
+                    props.fiscalYearStart
+                );
+                dateRangeKey = formatYearToFiscalYear(fiscalYear);
             } else if (props.dateAggregationType === ChartDateAggregationType.Quarter.type) {
                 dateRangeKey = `${dataItem.year}-${Math.floor((dataItem.month - 1) / 3) + 1}`;
             } else { // if (props.dateAggregationType === ChartDateAggregationType.Month.type) {
@@ -168,6 +177,8 @@ const allSeries = computed<TrendsChartDataItem[]>(() => {
 
             if (props.dateAggregationType === ChartDateAggregationType.Year.type) {
                 dateRangeKey = dateRange.year.toString();
+            } else if (props.dateAggregationType === ChartDateAggregationType.FiscalYear.type && 'year' in dateRange) {
+                dateRangeKey = formatYearToFiscalYear(dateRange.year);
             } else if (props.dateAggregationType === ChartDateAggregationType.Quarter.type && 'quarter' in dateRange) {
                 dateRangeKey = `${dateRange.year}-${dateRange.quarter}`;
             } else if (props.dateAggregationType === ChartDateAggregationType.Month.type && 'month' in dateRange) {
@@ -397,7 +408,7 @@ function clickItem(e: ECElementEvent): void {
         }
     }
 
-    const dateRangeType = getDateTypeByDateRange(minUnixTime, maxUnixTime, userStore.currentUserFirstDayOfWeek, DateRangeScene.Normal);
+    const dateRangeType = getDateTypeByDateRange(minUnixTime, maxUnixTime, userStore.currentUserFirstDayOfWeek, userStore.currentUserFiscalYearStart, DateRangeScene.Normal);
 
     emit('click', {
         itemId: itemId,