Add TimeSelector and ScheduleModal components with tests

- Implemented TimeSelector component for selecting time with AM/PM toggle and minute/hour increment/decrement functionality.
- Created ScheduleModal component for scheduling chores with options for specific days or intervals.
- Added utility functions for scheduling logic in scheduleUtils.ts.
- Developed comprehensive tests for TimeSelector and scheduleUtils functions to ensure correct behavior.

frontend/vue-app/src/common/scheduleUtils.ts

@@ -0,0 +1,123 @@
+import type { ChoreSchedule, DayConfig } from './models'
+
+/**
+ * Returns the JS day-of-week index for a given Date.
+ * 0 = Sunday, 6 = Saturday (matches Python / our DayConfig.day convention).
+ */
+function getLocalWeekday(d: Date): number {
+  return d.getDay()
+}
+
+/**
+ * Returns true if the interval schedule hits on the given localDate.
+ *
+ * Anchor: the most recent occurrence of `anchorWeekday` on or before today (this week).
+ * Pattern: every `intervalDays` days starting from that anchor.
+ */
+export function intervalHitsToday(
+  anchorWeekday: number,
+  intervalDays: number,
+  localDate: Date,
+): boolean {
+  const todayWeekday = getLocalWeekday(localDate)
+
+  // Find the most recent anchorWeekday on or before today within the current week.
+  // We calculate the anchor as: (today - daysSinceAnchor)
+  const daysSinceAnchor = (todayWeekday - anchorWeekday + 7) % 7
+  const anchor = new Date(localDate)
+  anchor.setDate(anchor.getDate() - daysSinceAnchor)
+  anchor.setHours(0, 0, 0, 0)
+
+  const today = new Date(localDate)
+  today.setHours(0, 0, 0, 0)
+
+  const diffDays = Math.round((today.getTime() - anchor.getTime()) / 86400000)
+  return diffDays % intervalDays === 0
+}
+
+/**
+ * Returns true if the schedule applies today (localDate).
+ * - 'days' mode: today's weekday is in day_configs
+ * - 'interval' mode: intervalHitsToday
+ */
+export function isScheduledToday(schedule: ChoreSchedule, localDate: Date): boolean {
+  if (schedule.mode === 'days') {
+    const todayWeekday = getLocalWeekday(localDate)
+    return schedule.day_configs.some((dc: DayConfig) => dc.day === todayWeekday)
+  } else {
+    return intervalHitsToday(schedule.anchor_weekday, schedule.interval_days, localDate)
+  }
+}
+
+/**
+ * Returns the due time {hour, minute} for today, or null if no due time is configured
+ * for today (e.g. the day is not scheduled).
+ */
+export function getDueTimeToday(
+  schedule: ChoreSchedule,
+  localDate: Date,
+): { hour: number; minute: number } | null {
+  if (schedule.mode === 'days') {
+    const todayWeekday = getLocalWeekday(localDate)
+    const dayConfig = schedule.day_configs.find((dc: DayConfig) => dc.day === todayWeekday)
+    if (!dayConfig) return null
+    return { hour: dayConfig.hour, minute: dayConfig.minute }
+  } else {
+    if (!intervalHitsToday(schedule.anchor_weekday, schedule.interval_days, localDate)) return null
+    return { hour: schedule.interval_hour, minute: schedule.interval_minute }
+  }
+}
+
+/**
+ * Returns true if the given due time has already passed given the current local time.
+ */
+export function isPastTime(dueHour: number, dueMinute: number, localNow: Date): boolean {
+  const nowMinutes = localNow.getHours() * 60 + localNow.getMinutes()
+  const dueMinutes = dueHour * 60 + dueMinute
+  return nowMinutes >= dueMinutes
+}
+
+/**
+ * Returns true if extensionDate matches today's local ISO date string.
+ */
+export function isExtendedToday(
+  extensionDate: string | null | undefined,
+  localDate: Date,
+): boolean {
+  if (!extensionDate) return false
+  return extensionDate === toLocalISODate(localDate)
+}
+
+/**
+ * Formats a 24h hour/minute pair into a 12h "X:XX AM/PM" label.
+ */
+export function formatDueTimeLabel(hour: number, minute: number): string {
+  const period = hour < 12 ? 'AM' : 'PM'
+  const h12 = hour % 12 === 0 ? 12 : hour % 12
+  const mm = String(minute).padStart(2, '0')
+  return `${h12}:${mm} ${period}`
+}
+
+/**
+ * Returns the number of milliseconds from localNow until the due time fires today.
+ * Returns 0 if it has already passed.
+ */
+export function msUntilExpiry(dueHour: number, dueMinute: number, localNow: Date): number {
+  const nowMs =
+    localNow.getHours() * 3600000 +
+    localNow.getMinutes() * 60000 +
+    localNow.getSeconds() * 1000 +
+    localNow.getMilliseconds()
+  const dueMs = dueHour * 3600000 + dueMinute * 60000
+  return Math.max(0, dueMs - nowMs)
+}
+
+/**
+ * Returns the local date as an ISO date string (YYYY-MM-DD) without timezone conversion.
+ */
+export function toLocalISODate(d: Date): string {
+  const year = d.getFullYear()
+  const month = String(d.getMonth() + 1).padStart(2, '0')
+  const day = String(d.getDate()).padStart(2, '0')
+  return `${year}-${month}-${day}`
+}